Everybody is selling "sex sells", and yes it does.
But it goes beyond that, film want it or not is art, would you censor art or sculptures that depict nudity?
Writers and filmmakers are artists expressing their views thru a lens, and if their views contain sexuality or eroticism, what shouldn't they show it?
It's not like actors are forced to do this scenes or that people are being forced to watch them, but you can't censor an industry because YOU have a problem with it, that's what Nazis and communist do.
Art should be free and uncensored, I don't think you have watched many European films where nudity is almost always part of the story, if you want to change the world, you choose the wrong battle.
Besides, people are so hypocritical, they see people, sometimes even kids being blown apart in a violent movie, but that's okay, you see a pair of breasts, or private parts and people yell bloody murder.
Remember what John Lennon said:
"We live in a world where we have to hide to make love, but violence is practiced in broad daylight."