Is self-interest a bad thing? We want our leaders to be pure and good, but at the same time we want them to be effective, and to be effective you often have to be ruthless and not bound by ideology or the same morals that we pretend to hold ourselves to.
But once a culture develops sufficiently to become skeptical, the idea of censorship becomes less attractive. To suppress a book or a picture or a sculpture or a play or a film is a terrible act of aggression against the artist who created it. This is a miming of capital punishment; it destroys the life that has been emanated by a life.