Hang about, there is a double standard here. People are complaining about how they don't want sex scenes in a game unless they are well written into the story and have a proper meaning. The same mentality is not taken in regards to scenes of violence or action though - there doesn't have to be any justification for it; as long as it looks cool enough, people don't tend to care. Well, why can't the same be for sex scenes?
The question is about realism and arousal factor of sex scenes, and less about the role they play in a story. As far as I see it, if they can make a sex scene in a game sexy, why not? Like action scenes, it only needs to achieve what it attempts to do (be cool, be arousing etc.) to become acceptable. That is the case in movies, anyway.