Hm, can't really see a method to change the way hookers work in GTA, they're like the gun store or clothing store NPCs, they are there just there for a function like lots of the NPCs. I guess one could imagine a backstory for the nameless whore on the corner. They definitely could do it with the strippers that are the 'girlfriends' in 5, though.
So I guess removal is the only option to resolve this perceived problem.
As for good writing in games, depends on the game - and audience, sometimes they aren't too fussed about it. UT/CS/Quake are fun games and doesn't need writing as the aim is just on the skill contests, most RPGs not so much. Don't think I've met many people that play GTA mind the story much more than they would an action flick (there are some entertaining NPCs, though) and mainly focus on other things in the game on, free-roaming or shooting or stunts, etc.