A lot of art I've seen makes the viewer face the thing she or he doesn't like in order to evoke an emotion or thought. And a lot of those topics that "should be excluded" are very good at that.
(Sigh)
Often great art makes people involves showing people think they don't like and that outrages them. The problem is that many "transgressive" and "controversial" artists today think it's the other way around: that if you show people things they don't like, then you are doing great art.