It would be abused. A button that allows you to give a takeback would be better than issuing a takeback request, but I don't like either.
Should there be a 'take back move request' button?

Yes! Mouse slips happen all the time. I hate to see a good game turn bad even when I'm winning. I would go so far as to propose a "give back" button in case the opponent is too stoic to ask.
In the interest of fairness though. The time it takes to go through the take back process should be charged to the blunderer so that there can be some kind of incentive for careful play.

It would be abused. A button that allows you to give a takeback would be better than issuing a takeback request, but I don't like either.
Could it be abused any more than draw requests?
What if it was a once per game deal. You press it once, the opponent gets the notice, and ignoring it is an automatic decline. And let's say people could disallow all such requests in their profile settings? How many player do you think would allow the option (where, denying it to others would also withhold from you from ability to make the request yourself)? Don't get me wrong, I'm used to the school of hard knocks and probably would not use it for myself, but not sure I'd want to deny it to others.
Might be good in the hands of strong players who know that the opponent makes typically excellent moves, and would forgive an obviously uncharacteristic blunder for the sake of preserving the quality of an otherwise excellent game.

no, that can lead to unnecessary arguments. i might as well suggest that there should be take back requests in tournament and world championships.

Not in rated games. In unrated games, fine.
"Mouse slip" is no excuse: you don't have to drag and drop to move! Just click the piece you want to move and the square to move to, it is foolproof - well, at least in executing the move, it can still be a blunder.
BTW has the way the board works changed? Because I noticed recently when you click on a piece to move and change your mind, and quickly move another piece in bullet games, your selection tends to stick.
Before it seemed the behaviour was different. If I clicked on a piece to move, and then I left it, it would no longer be selected, or active.
Has anyone else experienced this?

What do you think of the idea of chess.com adding another button to games that allows a player to request that the other player allow them to take back a blunder?
The obvious flaw in the idea is that, you might request a take back, and I would give it. But when I request one, you could just decline.
In a game you would have to assume both players are fair.

What do you think of the idea of chess.com adding another button to games that allows a player to request that the other player allow them to take back a blunder?
The obvious flaw in the idea is that, you might request a take back, and I would give it. But when I request one, you could just decline.
In a game you would have to assume both players are fair.
I was just asking the big question initially not pondering the design or implementational logistics. It could be made automatic that giving somone a take-back would automatically enable your own takeback so it would not need to be approved by the opponent, throught magic of software engineering.

turn based you can turn (click) it back but on live chess I don't know.
I am following Estragon's description: Just click the piece you want to move and the square to move to.
Did live chess always work like this? I have always played by dragging the pieces, so that if you change your mind you don't accidently move the wrong piece. Maybe chess.com to counter mouse slips have implemented the starting square landing square thing.

What do you think of the idea of chess.com adding another button to games that allows a player to request that the other player allow them to take back a blunder?
Nonsensical idea!...reminds me of the threads by a perfect idiot

What do you think of the idea of chess.com adding another button to games that allows a player to request that the other player allow them to take back a blunder?
The obvious flaw in the idea is that, you might request a take back, and I would give it. But when I request one, you could just decline.
In a game you would have to assume both players are fair.
I was just asking the big question initially not pondering the design or implementational logistics. It could be made automatic that giving somone a take-back would automatically enable your own takeback so it would not need to be approved by the opponent, throught magic of software engineering.
That has the problem, that if a take back is guaranteed for you, I might take the risk of losing than giving you a take back if you are a stonger player.
As a weaker player, I will make mistakes, many more than you. But as a stronger player, you might miss a checkmate, and if you have take back, you could just undo, go back and mate, leaving me no chance.

If you're playing online chess, there's an option to play takeback games which, of course, are unrated. But no, I don't want a "takeback request" button, because every bad move someone makes will result in them using that button.
If I make a bad move, or have a mouse slip which results in a bad move, I just suck it up and either play on or resign, and learn to not do that the next time.

Mouse slip exist, it is true.
But it is one in 100 games, for blitz where you have to move fast, if not less.
So get over it.
Otherwise, having the possibility to offer a takeback is the less awkward way, but there would still be abuse. For example a higher rated offering a take back after the lower rated has played a winning though unclear sacrifice : "Well tried, but it doesn't work. That's so pretty, I allow you to continue the game otherwise". Even if the lower-rated player doesn't fall for it, that is clearly abuse.

U have got to be kidding w/ "take-back button"......
Not really. I just wanted to see the different opinions / thoughts on it.
You're misquoting me, and omitting the 'request' part. It was more like giving players the ability to agree to a taken back move such as in an informal OTB game where that happens sometimes.

I think it would be fine if they had an "Unrated: Take Back." It has to be before the other player moves, though. I think it would be a good teaching tool for people who are helping weaker players. This teaching idea could be done in the analysis board easily enough, but not everyone has such a thing.
What do you think of the idea of chess.com adding another button to games that allows a player to request that the other player allow them to take back a blunder?
Note: I'm deliberately keeping the question general and not delving into the various kinds of conditions/restraints that might be involved, such as allowing it to be used only once, and automatic-decline, such as with draw requests, or a requirement of mutual agreement to enable the option for a game, etc...
What made me ask the question is that if two opponents are playing OTB in an informal (e.g. non-tournament) setting, sometimes they agree to allow one of the players to take back a move to preserve the overall value of letting a game proceed without being ruined by an uncharacteristic blunder, or noob mistake.