You don't have to be addicted to it, but if you want to play serious OTB games, you absolutely should be able to play 3-5 minute games. Otherwise you can spend almost 5 hours playing decent game and gaining advantage and then ruin it all in the last 5 minutes ( I did that once, after that I improved my blitz).
You want to improve Ur last 5 Min's in a longer OTB game, learn how to play your endgame better, then u wont make so many mistakes. Blitz games are more for fun then for skill development.
perhaps...a few here and there. but unfortuantly it is what people play the majority of the time. Here is the crazy thing. Majority of people who play here play blitz and their blitz ratings are higher than their long game ratings. So unlike yourself blitz has made their long game suffer.
My blitz rating is far higher because I don't play long games too much. I havent' been playing the 3 days per move much lately either(I can't always get to a computer and I tend to "lose the position" after leaving). I play blitz and 10 min games mostly now. 10 mins is PLENTY of time to make a good plan and execute it. Even in 5 mins there is time to make some good planning.
One of the people I play with was saying how she thought blitz was all about speed and not about skill. I think a greek gift combined with a Double bishop sacrifice a few mins later changed her mind on that.
Blitz is great for getting yourself to key in on the important parts of the position(and that is after all what ALL chess is about). If you don't you ARE toast.