Ever wonder why movies don't have as much nudity as they used to? [...] The answer is Wal-Mart. In 2007, the six major studios made $17.9 billion in DVD sales, $4 billion of which was from Wal-Mart, the world's largest retailer. Wal-Mart has a policy which forces any film with sexually related nudity away from high-visibility shelf space and into more obscure "adult" sections of the store. (This is so as not to offend mothers, who are there not to buy low-margin DVDs but high-margin items such as clothes, toys, or electronics...)
From a review in the Weekly Standard of a new book by Edward Jay Epstein, The Hidden Financial Reality Behind the Movies.