Gromit - your point is a fiar one.
But in a culture like ours, there are a number of significant events that are so huge in terms of their negative impact, that they simply defy efforts to dilute their effect with humour, and for that reason, it is generally accepted that it is better not to try.
For that reason, no-one is doing Jimmy Saville impressions any more. No British radio stations play Gary Glitter records. No-one makes jokes about the Holocaust, or Lockerbie - and so on and so on.
I firmly believe that some tragedies are of sufficient magnitude that they defy any concept of levening by humour, and 9/11 certainly fits into that catagory.
Yes, some aspects of modern culture, certainly including music, are designed with an inbuilt 'shock' concept.
But that is an absolute world away from dressing up (just think about that concept for a moment) as a recent tragedy. That does not equate with humour as I understand the term, and I think I am far from alone in that view.