"....and the event has been well planned then I can't see the harm in it."
Fair comment and provided nothing goes wrong there would be no harm.
The B-52 accident was probably practised in the sim and many times over in the aircraft, given the almost limitless resources of the US military and we all know the result of that display.
When it does go wrong, not only the aircraft is broken but also probably the whole airline company with mass redundancies, increased insurance premiums etc., all for a couple of seconds of "fun". I have trouble understanding why airlines allow this sort of display flying (assuming this display was authorized) to take place when it all could go wrong, with the resulting consequences.
The simulator is the place to get "yourself off" with this sort of flying if required, not in an expensive aircraft, with massive third party implications.