Why wouldn't it be? There's plenty of porn sites out there, and if it's just picts of breasts and butts, then the content is legal. That would only become a problem if it showed sex acts. But it has been legally ruled that the human body by itself is considered art.
The obvious question is access to this by kids. Again, there are tons of porn sites. Go to Gogle.com, click on video at the top and type in porn and you would be quite surprised by what you see.
