I don't think it's a black and white question. I can't think of a single game that I play because of the sex scenes. This doesn't mean that I dislike them, in fact I want them, just not at the cost of gameplay/story/characters.
As for story driven games, while I do tend to focus more-so on them. I feel as if the story isn't as important either. While I do want the story to maintain some bit of inconsistency and coherency, other than this I can enjoy a bad story just as much, if not more, than many of the "good" stories portrayed on this site.
What I am more interested in is characters. If I dislike the characters chances are, I am going to dislike the game. No matter how good the sex scenes or story may be. A good character gets my attention and enhances the story and sex scenes significantly.