My favorite game of all time, The Witcher, is definitely in the category of "Games for Adults" and has a bit of nudity in it. It's not gratuitous, and you could go most of the game without seeing any, but it's there and it serves a purpose and it's not shoved in your face, so I am totally fine with it.
I do, however, have a problem with an industry (or a country, for that matter) that thinks it's bad to show boobies in a game, but it's perfectly okay to let a 6th grader pretend to hack someone up with a machete. What would happen if we took out every instance of violence and blood in a game and replaced it with bare breasts? Hmmm...