As definition what is moral or inmoral is different for any human being there is no real question. For example Maplethorpe work will be see differently not only from each human being individualy, but also USA, Asia, Europe, Africa, West, East... and individual societies in those continents or parts of the world will have different opinion about morality. So, who is THE JUDGE who will say something is moral or inmoral? Not even God, because people belive in different Gods (or same God but have different rules how to worhip it). So, there is no real dillema. If you can not buy David Hamilton books in USA or Europe anymore, you can go to Japan and buy it(just example from one of discussions from this forum). And is that means society in USA or Europa is more moral than in Japan? Very dangerous question. I think not. And how society can raise question about itself if artists or philosophers don't question moral boundaries of that society, with their work? Are polititians or religious leaders qualified to tell to each of us what is moral or not? Are artists? And who is that ultimate judge?
As long as it is legal (well even that can be questioned)...