Been to a lot of indoor meets with our kids, and I've never remotely felt unsafe at, around, or watching the matter throw. We are regulars at Kent State, Akron, and Youngstown State, and there is no way a hammer is clearing the structure(s) they use. Stands for the throws are also facing the throws, and set a good distance from the actual netting/structure. 
I would agree that it is not the event itself that is the problem, but the setup. Even spectator wise, there are folks making sure no one enters the open restricted zone while the throws are happening. 
I can't believe this is anything but a complete safety-failure on part of the venue.