Kind of on the other side of the coin there are people leaving because of what they see as censorship. Is not the best way to solve this is to use peer pressure? We are all here because we like CG, if there where more professionals posting images on the site it would encourage more diverse content from everyone else and move away from images that cause offence. I'm not a professional but I'm sure they like free publicity, for example "picture of the day" type content on the front page would give them opportunity to show their work.