I would agree with what you are saying, the situation with the Viggen was strange to say the least, but the main thing is if the weather gods decide not to play ball, then there`s very little that can be done.
The bad weather for Sunday was forecast well in advance, at least mid-week if I recall, the irony is Sat`s weather was much better, but it was billed as a practise day.
Any outdoor event is at the mercy of the weather, sadly some sections of Joe Public don`t read, or choose to ignore the small print. There does seem to have been an increase in bad weather during our summer months, and several airshows have suffered because of it, it does seem to be more common.