We've only seen a small portion of the city, really - there's bound to be more seedy parts of town. Eh. But. I certainly won't be using it, it's not GTA - wherein I don't really use that, either. I'm not fifteen.
I find things like Brothels and Drugs ground a game for me, with it being a part of every day life for many.
In that, I don't mean people need to be all drugged out and lurking in brothels day in day out in the game, but seeing some of it would seem right to me since pretty much everyone I know dabbles in enhancements and such things IRL (I'm in the event/media/entertainment type crowd, it's a debaucherous lot of humans at times).
I'm definitely not saying those things should be glorified or experienced in some form of weird 'wasted-o-vision' like in some games, but them being in the game
at all really helps my immersion in the game world.
Wanting things that truly immerse you in a game doesn't mean you're being immature - sex and drug use are normal parts of the adult world we live in.