Perhaps what I'm trying to say is that artists should indeed have a moral compass, but in a free society, that moral compass should probably be internal rather than external.

I agree wholeheartedly that the compass should be internal rather than external. I also think that artists should always check their compasses against others', to see if maybe theirs needs tweaking. I think I've stretched the compass metaphor as far as I can. :)

It can contain such messages, and often does, but art for art's sake is just as valid as art for some higher purpose.

Yeah, but I'd argue that art for art's sake cannot, by my own definition, be harmful. Because if it starts doing harm, then it was never for art's sake. Shvarts' little stunt was not art, because it was not done for art's sake. It was done for politics, for attention, for celebrity, for ego. But none of that was done for the sake of art.

I'm not one who necessarily needs a higher message, either. Sometimes a pretty picture or a lovely song is enough in and of itself - but I do think it's necessary for an artist to always examine themselves to make sure that their idea of beauty isn't making them into ugly human beings.