I really disliked the whole gangsta' theme of San Andreas. The clothing options and vehicle customization I can understand, but that's it. Personally, for me San Andreas was a bit of a step down in the series. To me, all I really care about is a good story and a bit of in-game world immersion, none of the other fluff like gangs and gyms. Those are all useless to me, and I've rarely used them. The story was pretty decent, if you can say that. It was pretty much just Carl getting pushed into things by other characters.
It seems to me, all everyone cares about is having an Infernus parked in front of their huge mansion while they go out and shoot gang members. Where's the realism in that? Having a good story wrapped around a good protagonist is enough to make me happy.
As for Vice City coming back, I'm all for it. It still remains one of my favorite PC games, next to IV. Rockstar would be making a very huge mistake to not bring it back.