I have a thought for you.

Murder is illegal. 
But you take a picture of somebody committing the act of murder, they'll put you on the cover of Newsweek.
You might even win a Pulitzer Prize. 

Sex is legal. Everybody's doing it, or everybody wants to be doing it huh?
Yet you take a picture of two people in the act of sex, or just take a picture of a woman's naked body and they'll put you in jail