Women do NOT want to free their nipples.

Maybe they would in a perfect world where everyone had perky breasts like Rihanna but the reality is most women don't. A big + of using a bra is it makes breasts look better than they actually are. It's just like make-up.
They also do not want their breasts to lose their super effectiveness on guys' dicks since it's one of their most beloved secret weapons to manipulate their boyfriends' poor minds.Take a look at some African tribes where being topless is the norm for women. Their men are used to seeing their breasts since birth, they don't have the magical effects they have on men in most places of the world.
I hope my post won't trigger your feminist side.

I think nipple censorship in movies and other media is very unnecessary most of the time but women cover their breasts for a reason in real life.