Accidents happen, that is life.
Why do people who do not own or fly the aircraft want them grounded and deprive millions from seeing them in their proper environment.
Very rarely do airshow accidents involve public casualties, probably far less a proportion than car race/rally accidents. One member of the public killed in an airshow accident is headline news, five people killed in a car rally accident is on page 5. Are we to ban motor racing?
If the public is not involved it is nobody's business but the willing participants.
An aircraft in a museum is just a dead lump of metal - even collections in hangars and museums have been destroyed by fire.
In the air it is living history
Just on that particular accident. It was not crowded airspace, they were all going in the same direction, well spaced, on a briefed course with very little danger. I have no idea where the P63 was supposed to be but I suspect the fighters may have had a stream of their own joining the bombers in front of the crowd 500 feet higher. Either the B17 was too high or the fighter too low but the bomber was certainly in his blind spot underneath. Human error like 99% of the 200,000 car accidents around the world every day.
Here is a clip showing amateur private pilots not only in formation which is practiced and controlled but everyone doing their own thing landing in crowded conditions far closer and more risky than a flyover - and nobody died.
https://www.youtube.com/watch?v=3o51KWkTpSY