I think the promise of movie nudity absolutely sells more tickets. They can't show it on broadcast network TV because of censors and stuff - the most you can do is tease it or imply it. Movie audiences are generally literate enough to know what to expect. I didn't see any explicit nudity in any of the TV trailers for Friends With Benefits, but I saw it implied all over the place, so I would assume, without having seen the film, the odds of there being nudity in it are about 110%.
Nudity doesn't seem to be nearly as prevalent as it was back in the day. I've noticed since the 90s there has been a lot of teasing of nudity, only to see RATED PG-13 at the end of a trailer.
Of course, back in the early 80s, there was nudity in PG movies. We've actually backtracked quite a bit in terms of nudity. Now they're painting it on!
Cable TV seems to have really pushed the envelope on it, tho, so at least there is that.