I think dorming is a good experience. I mean I had a forced triple (I'm at Fordham University) and while I really detested one of my roommates, I found a really great friend in another. You also meet people that are like and not like you and learn about yourself by learning with other people your age.
On another note, I don't think it's necessary. If you don't care about drinking and partying and the college experience and you'd rather commute, go for it, you aren't missing too much.
Fellow NYer dorming here.
I'm going to St. Francis in Brooklyn and I dorm in their dorm house at St. George Housing or whatever. I don't know if it's just this place since I haven't been to other campus dorms here in the city, but the rooms here are smaller then the other dorm houses I've seen/stayed in.
Do I think dorming is a good experience? Yeah, if you're moving to a new city/town/state to go to that school. Dorming is an excellent way to meet people. You're surrounded by people that don't have friends there either. They want to make friends just as much as you do.
Will you get shitty roommates sometimes? Well sure but that's a learning experience and in life you'll have to learn to just deal with shit. Well, unless you're rich.