I agree with Butch at work; it's very upsetting to imagine a world where everything potentially offensive was expunged from the public record, musical, historical or otherwise. By learning (& hearing) about the way things USED to be, we aren't advocating a former state of affairs, but by refusing to even look at them we may well lose the opportunity to learn from them, becoming wiser and more genuinely tolerant, as opposed to simply being superficially frightened of giving offense.