A bare Vulcan backside or a side-shot of bare breast may bring in viewers, but if there's no story to back it up you'll see the audience drift away almost immediately.
I'm of the opinion that if it's story-driven, i.e. if the more graphic depiction adds to the story, then it should be shown. If the sex/nudity is unsupported by the story, though (used for shock value, in other words), forget it. It doesn't belong on the kind of TV we're talking about, and is, in fact, a cheat.
I am
Dawg