In agreement with everyone who has pointed to the false dichotomy, I am concerned about the "who decides" in the initial post.
When we transfer to others the responsibility of deciding what's "good" for us, we open the door to Big Brother. This is the first step toward censorship and curtailed personal liberties. With our acquiescence, those who supposedly know better begin by banning pornography and may end up by banning anything that implies a potential challenge to the regime's -any regime's- vested interests.
I think it is up to parents to "draw the line" as to what their children should listen to and watch. Yet at some point parents themselves need to openly discuss such matters with their children. Keeping them in ignorance may prove dangerous, because those who cannot distinguish between values and non-values are often an easy prey to exploiters.
An additional note is that the concept of pornography has changed over the years and will continue to change. Historian Arnold Toynbee often spoke about "the swing of the pendulum," meaning that we are constantly moving between exceedingly permissive and exceedingly repressive behavior. We do not seem to be able to reach a happy medium, and this should make us extra careful about what we condone or condemn.