Good art speaks to all of us. And we might not always like what it says. Robert Rauschenberg and Andy Warhol upset people with their graphic portrayals of murder and death. More recently the neo-expressionists have made visual statements about sex and violence. Such art can bring us to a level of deeper understanding.
Art has a voice.
It is created with the imagination and is just as much a part of humankind's makeup as are the tongue, mouth, larynx and lungs with which we speak. A free society is kept in check by critics and visionaries, some of whom are artists. It has a spiritual aspect that is better understood by the artist than by any other, because of continuing ties to centuries-old traditions. Living cultures do not stagnate. They change and develop, but those that are long-lasting also maintain tradition.