I was a doller, and the reason I quit has more to do with the atmosphere of most dolling communities than the art itself. Sure there are plenty of crappy dolls out there, but I've met way too many people who absolutely hate even the idea of dolls because they're stiff and uncreative and lacking effort/work, etc, and that's just generalizing too much IMO. I was a doller for around two years and that's when I learned most pixel art techniques I know/use now, so as an art form it's really not as evil as most people would imagine. There's crappy stuff in every kind of art community, like someone said earlier, so targetting this much hate toward dolls is unreasonable.
I said I disliked them, but only because most dolling forums have so much drama involved, it's what turned me off in the first place. Also there is a lack of serious cc in most places. It's not ALL "omg kawaii" but a lot of it is compliments without any real feedback about the image. A friend of mine who'd quit dolling for a while to do some 'staight' pixelling said she went back to dolling because she didn't like how on pixeljoint everyone went straight to whats wrong with her piece instead of sandwiching cc in compliments (goodbadgood). And I personally don't see that as a problem, so that's why I stayed. Many dollers, like someone mentioned, are really young and so are really sensitive about what you say, and also because they're so young, it's not a really great place to continue learning once you've reached a certain point. At least that's how it was for me.