Would you care to elaborate on how this would be a problem kaynight?
Players who make you wait to win

I don't see how this falls in the category of a "crazy" individual preference? No, that won't be the next suggestion, the current one has hardly been addressed... The prompt time can be appropriate to game time. So in a 30-minute game it would arise as a result of 5 minutes of inactivity, while in a 45 / 45 game it would arise as a result of 10-15 minutes of inactivity. It's not a giant warning, it's a silent prompt that pops up that the player has to click to insure the player is still there. Your "slipper slope" is a bit extreme for the suggestion made.
Though, I admit that if a player really wanted to push the issue, they could sit with the chess game in a reduced size window, waiting for the prompt, just to make sure their opponent has to wait through the remaining game time to win. However, even that would reduce the number of players who do this. If you are going to sit and watch the game anyways, you might as well play or resign and play another game. Most players who make another player wait to win, walk away from the computer.
Chess.com has a current system in which players who do this are 'flagged' in some way. Though I don't know the extent to which flagging affects the player.

I think the best way to answer this question, op, is simply to point out that internet chess is meant to parrallel OTB chess.
in OTB chess, despite some very LONG time controls you could Absolutely run down the clock on your own move- just to be a jerk. An arbiter couldn't and espacially wouldn't intervene.
its rude but its life. and Is infinitely more rude irl. online, even in the longest of time controls. you can open another tab and do other things-- with the occasionally check on the game.
Your suggestions to have chess.com remind a player that he hasn't moved in many minutes won't be implemented, and your incorrect that players are 'flagged' for not moving
players are "flagged' for Abandoning the game- where your opponent has closed the tab, or even left the website. in that case, your opponent has a smaller amount of time (I think its 3 minutes) to return to the game, or chess.com will call the game "abandoned" and give you the win...
since nothing will happen about it, I encourage you to simply accept that , very unoccasionally, your opponent will be a real jerk about losing- and make you Wait the Whole time control to get the win.

Now I'm not one to devalue the importance of patience. Unfortunately, there are players of the trollish persuasion that upon realizing they have lost, will neither resign nor move. For any game of 10 minutes or less, this is generally not an issue. For the game I am currently waiting on (and using the time to write this post), a standard 30-minute game, this can be quite annoying. I understand there is no fool proof way to avoid this as players will always find a way to aggravate other players (especially ones who have just defeated them). I do however come with a suggestion: After 5-minutes of inactivity a prompt could open up on the offending players screen asking them to click a button to insure they are still there. This way they cannot just walk away from the computer. If they are going to make me wait out the remaining time, at least they have to sit there and wait as well! Or, in the name of fairness, a button would become available to the offended player in which he could poke the offending player and then the prompt would appear. This way, if one player has asked to step away from the game for 5+ minutes the waiting player could potentially allow the player time to return. Thoughts? Other suggestions?
You agreed to play an online game of chess.
You ageed to a time limit.
Quit calling people "offenders", as you have no idea what they are doing, or what may have happened.
if you dont have the patience for longer time controls, play blitz/bullet.

Your suggestions to have chess.com remind a player that he hasn't moved in many minutes won't be implemented, and your incorrect that players are 'flagged' for not moving
Correct me if I'm wrong, but if a player 'quits' but does not move any pieces and lets the time run out they are flagged. At least, in the cases where a player has done this to me, I receive a message saying "so-and-so may have violated our fair play policy and their account has been flagged and may be restricted".

I think the best way to answer this question, op, is simply to point out that internet chess is meant to parrallel OTB chess.
in OTB chess, despite some very LONG time controls you could Absolutely run down the clock on your own move- just to be a jerk. An arbiter couldn't and espacially wouldn't intervene.
[...]
since nothing will happen about it, I enourage you to simply accept that , very unoccasionally, your opponent will be a real jerk about losing- and make you Wait the Whole time control to get the win.
Fair enough. It's something I have no choice but to accept. I wasn't complaining about it in the sense that I'm going to quit, or it's the end of the world. It was simply a suggestion.

Now I'm not one to devalue the importance of patience. Unfortunately, there are players of the trollish persuasion that upon realizing they have lost, will neither resign nor move. For any game of 10 minutes or less, this is generally not an issue. For the game I am currently waiting on (and using the time to write this post), a standard 30-minute game, this can be quite annoying. I understand there is no fool proof way to avoid this as players will always find a way to aggravate other players (especially ones who have just defeated them). I do however come with a suggestion: After 5-minutes of inactivity a prompt could open up on the offending players screen asking them to click a button to insure they are still there. This way they cannot just walk away from the computer. If they are going to make me wait out the remaining time, at least they have to sit there and wait as well! Or, in the name of fairness, a button would become available to the offended player in which he could poke the offending player and then the prompt would appear. This way, if one player has asked to step away from the game for 5+ minutes the waiting player could potentially allow the player time to return. Thoughts? Other suggestions?
You agreed to play an online game of chess.
You ageed to a time limit.
Quit calling people "offenders", as you have no idea what they are doing, or what may have happened.
if you dont have the patience for longer time controls, play blitz/bullet.
Okay, relax. Again this was a simple suggestion. Not a mutinous assault on chess.com and all players who quit but refuse to resign. They are, however, "offenders". Being an "offender" does not inherently make them a bad person when, as you said, life happens. However, and especially when a player might deliberately tell you "now you wait to win", some people are just deliberately ill-mannered. I play longer timed games specifically because I enjoy the added time to think and the quality of the game that both my opponent and I can play. This doesn't excuse someone being vindictive and quitting a game with 20-25 minutes left to play. I want to play for 30 minutes, not wait for an inactive game to end. I also realize that this may be a simple of truth of online chess and it's not something that's going to ruin the site for me. Hence it's a suggestion and not an ultimatum.

Now I'm not one to devalue the importance of patience. Unfortunately, there are players of the trollish persuasion that upon realizing they have lost, will neither resign nor move. For any game of 10 minutes or less, this is generally not an issue. For the game I am currently waiting on (and using the time to write this post), a standard 30-minute game, this can be quite annoying. I understand there is no fool proof way to avoid this as players will always find a way to aggravate other players (especially ones who have just defeated them). I do however come with a suggestion: After 5-minutes of inactivity a prompt could open up on the offending players screen asking them to click a button to insure they are still there. This way they cannot just walk away from the computer. If they are going to make me wait out the remaining time, at least they have to sit there and wait as well! Or, in the name of fairness, a button would become available to the offended player in which he could poke the offending player and then the prompt would appear. This way, if one player has asked to step away from the game for 5+ minutes the waiting player could potentially allow the player time to return. Thoughts? Other suggestions?
You agreed to play an online game of chess.
You ageed to a time limit.
Quit calling people "offenders", as you have no idea what they are doing, or what may have happened.
if you dont have the patience for longer time controls, play blitz/bullet.
Okay, relax. Again this was a simple suggestion. Not a mutinous assault on chess.com and all players who quit but refuse to resign. They are, however, "offenders". Being an "offender" does not inherently make them a bad person when, as you said, life happens. However, and especially when a player might deliberately tell you "now you wait to win", some people are just deliberately ill-mannered. I play longer timed games specifically because I enjoy the added time to think and the quality of the game that both my opponent and I can play. This doesn't excuse someone being vindictive and quitting a game with 20-25 minutes left to play. I want to play for 30 minutes, not wait for an inactive game to end. I also realize that this may be a simple of truth of online chess and it's not something that's going to ruin the site for me. Hence it's a suggestion and not an ultimatum.
Unfortunately with online chess you have the players that will let the clock run out. Some people just get online butt-hurt more than other i guess. You are not the first to bring it up, and i doubt youll be the last :-) This is brought up constantly.
Keep in mind that the rediculousness you experience online, doesnt happen in person at OTB games/tournaments. The reason is obvious.
I get your point, and I kinda like the direction it is going.
Something that could perhaps be implemented is that the mouse pointer has to remain on the chess.com interface most of the time – or maybe it would even just be enough to give the automatic flags more weight.
However, I'd reckon most of the solutions would bring more unfairness than fairness, to players with a weak connection etc. And as patzer pointed out, in real life your opponent could choose to do exactly the same, and it would be completely fine and according to the rules. So just make sure that you have your sound on to eventually hear if (s)he chose to make a move, and go read about infinite-dimensional holomorphy on Wikipedia in the meantime ;P

Your suggestions to have chess.com remind a player that he hasn't moved in many minutes won't be implemented, and your incorrect that players are 'flagged' for not moving
Correct me if I'm wrong, but if a player 'quits' but does not move any pieces and lets the time run out they are flagged. At least, in the cases where a player has done this to me, I receive a message saying "so-and-so may have violated our fair play policy and their account has been flagged and may be restricted".
as far as I know,
you are wrong. chess.com only flags accounts if they disconnect ("abandon") and can't get back to the game within three mintues (I think the waiting time is even shorter in blitz).
this has happened to me once -
I had a power outage, my PC crashed. I tried to get back into the game, but the computer went through some diagonstic program- I couldn't stop the program and I wasn't able to log in for about 10 minutes....
so I had the warning you are talking about, and the opponent had to wait 3 mintues for his win.
... no if the oppponent wants to make you wait 27 minutes in a G30 game after he hung his peice in move 5- there will be no warnings of any kind from chess.com.

Okay, relax. Again this was a simple suggestion. Not a mutinous assault on chess.com and all players who quit but refuse to resign. They are, however, "offenders". Being an "offender" does not inherently make them a bad person when, as you said, life happens. However, and especially when a player might deliberately tell you "now you wait to win", some people are just deliberately ill-mannered. I play longer timed games specifically because I enjoy the added time to think and the quality of the game that both my opponent and I can play. This doesn't excuse someone being vindictive and quitting a game with 20-25 minutes left to play. I want to play for 30 minutes, not wait for an inactive game to end. I also realize that this may be a simple of truth of online chess and it's not something that's going to ruin the site for me. Hence it's a suggestion and not an ultimatum.
by the way, like yourself I enjoy the longer game.
I spent a couple weeks playing shorter games, cause I had a cold, and I wanted to free up time for strudy.
I have lost 6/8games from time. thats enough (for me) of the blitz for awhile.
I'm tired of losing to time. I'll take the very occasional game where sometimes maliciously waits out the clock. besides many times in G30, people are more polite and courteous than the blitz crowd.
Now I'm not one to devalue the importance of patience. Unfortunately, there are players of the trollish persuasion that upon realizing they have lost, will neither resign nor move. For any game of 10 minutes or less, this is generally not an issue. For the game I am currently waiting on (and using the time to write this post), a standard 30-minute game, this can be quite annoying. I understand there is no fool proof way to avoid this as players will always find a way to aggravate other players (especially ones who have just defeated them). I do however come with a suggestion: After 5-minutes of inactivity a prompt could open up on the offending players screen asking them to click a button to insure they are still there. This way they cannot just walk away from the computer. If they are going to make me wait out the remaining time, at least they have to sit there and wait as well! Or, in the name of fairness, a button would become available to the offended player in which he could poke the offending player and then the prompt would appear. This way, if one player has asked to step away from the game for 5+ minutes the waiting player could potentially allow the player time to return. Thoughts? Other suggestions?