Very much agree with eRe4s3r's first sentence, and found the rest of this post very interesting and thought-provoking -- I didn't know any of this.
I do think the Telegraph piece is a bit naive, in fact deliberately crude. Titus Andronicus is spectacularly violent, yes, but in the most stylized, Senecan / Ovidian way - the violence isn't immersive or even imitable, and tends to evoke nervous laughter. It's also worth noting that plenty of alarmists in the 19th century did indeed bowdlerize Shakespeare and that Romeo & Juliet *has* been forcibly removed from school curricula. What do we exist for, collectively, other than to be a laughing stock for the next generation?
People with a propensity to violence are attracted to representations of violence. So are weak, unmanly aesthetes like me. The relationship between life and art is not altogether predictable. And of course artists themselves are reluctant to let go of the idea that what they do actually has an effect on people and on society, so they can hardly object very deeply to this tabloid version of the theory that art is actually powerful. Which, on the whole, it isn't, very.