Opening practice is one of the best things you get in return from playing a ton of short games...so you're right on the money there.
Though even before we get to answering the "Is is bad" questions ... what awesome little town of chess aspirations are you trying to get to in your life?
a- A USCF/FIDE rated player hoping to make a title one day (Expert or above)?
b- Be the guy who decimates everyone in his local city/town clubs?
c- Be the "I'm just enjoying the game and want to keep getting as good as I can get....don't care too much about being the best or winning tournaments" guy.
d- Be the "I'm just here for the scenery ... love the game and will keep playing it against opposition that is comfortable for me to have fun". (which is where I found myself after years of denying it! :))
If a) or b) are where you'd like to go, then you really need to play a ton of slow games (G/45 or more) as this is the regular diet for tournament players who want to climb the rating ladder. Ideally mix up a session with a few fast games and one slow rated game. Only playing speed and having reasonable ambitions about getting better is a little silly. Your brain is going to pick up a lot of bad and lazy habits ... you'll hand-wave more often than you'll calculate and when you reach positions where a long think is required, you're going to play them horribly ... which against strong opposition is equal to resigning.
If it is c) or d) or something less ambitious, then you can choose to be more flexible ... though you really learn a lot more in a slow game as your brain tends to "cement" patterns more efficiently if it is staring at each position for 1-2+ minutes as opposed to running past them in blitz-mode.
Some people just like being able to be more thorough with their analysis and with enough slow practice, this actually makes them better "fast" game players!
One last thought : If you must indulge in speed games only, play them with a small time-delay or increment (5 seconds is good) as it discourages habits like racing to flag or hoping that your opponent will fall for cheapos under time pressure (which does NOT happen as often with an increment or time-delay) so you're forced to really play with clean technique to outplay your opponent all the way till the end!
Is playing short games (5-0) detrimental to improving your game?
I used to play nothign but 20 min games. Then I became interesed in 5 min games. I now play far more of those than long games. I think they've helped me improve my openings by allowing me to experience far more mistakes per day than long games. Other than that, I don't know if they are also causing me to develop bad game-play in other areas.