Each to their own, but I wouldn't call what the MPAA does "censorship" (to my limited knowledge, that is; I'm not an American).
The MPAA issues ratings; it's up to the studio to decide whether to make cuts to a film in order to attain a particular rating. No-one forces the studio to make the cuts (Wikipedia: "The MPAA rating system is a voluntary scheme not enforced by law and films can be exhibited without a rating").
Sure, it might be commercial suicide to issue a film with a particular rating, but the right to free speech != the right to make lots of money.
The rating system is only "voluntary" in the sense that the government will decline to impose its own rating system as long as the private one meets the government's goals.
The MPAA issues ratings; it's up to the studio to decide whether to make cuts to a film in order to attain a particular rating. No-one forces the studio to make the cuts (Wikipedia: "The MPAA rating system is a voluntary scheme not enforced by law and films can be exhibited without a rating").
Sure, it might be commercial suicide to issue a film with a particular rating, but the right to free speech != the right to make lots of money.