Regarding the question " should are be censored in any way? " should definitely de considered by art galleries. If are is not censored then I believe that there should be a brief note regarding the ages that are applicable to the artwork. If the art is censored then the art can be seen by any ages if the parents allow it.
I really don't think so. By censoring you restrict creativity, and take away from the piece as a whole. Artist have made their pieces to be seen the way they are, and if that right were to be taken away then the artist shouldn't have made the piece in the first place. In regards to children, if their parents/figure of authority really feel that certain pieces are inappropriate then it is the responsibility of the parent/figure of authority to regulate their children. For adults, if it's really something that you feel is inappropriate then don't look. Once the line of harm or abuse has been crossed then it would be reasonable to do so, but other than that absolutely not.