Accidents will always happen at airshows no matter how many rules you put in place. In this case the rules appear to have kept the paying public safe.
Having seen the footage it does appear to be another barrel roll gone wrong, pilot error or mechanical failure? one can only speculate at this stage. Not a good manoeuvre down near the dirt at the best of times!
Even the best pilots make mistakes but the risks are understood. Any argument in favour of stopping aerobatic displays is sad to hear! The risks are relatively small probably the most dangerous part of a disciplined display pilots day is the drive to the airport.
My best wishes to the crew’s friends and family.