First of all, I have to mourn the loss of those who lost their lives in this tragic incident. I spent many a summer very close to that spot, while my step-mother was a teacher at the nearby Lansing College. Those traffic lights in particular, I remember well.
I have seen a lot of negative comments, both here, and in other places, mostly comments about how 'amateur' pilots should not be allowed to fly out-of-date military hardware. Well, for the record, Andy Hill, the pilot in this case, was a formation instructor, light aircraft test pilot, former RAF Harrier GR7 Instructor as well as a qualified instructor for the Jet Provost. He is also a British Airways Captain (A380/B757/B767), and has over 12,000 flying hours. Hardly an amateur.
Yes, airshows are inherently dangerous, and accidents do happen, but the organisers do whatever they can to minimise the risk involved, both to the pilots, the spectators, and the general public.
As for those who say that the aircraft shouldn't have been flying still, well, just remember that XH558, is only a few years younger.