Something like this is exactly why so many people attend these shows. Whether they want to admit it or not, most of the people watch these shows for the "what if something goes wrong." In a way it's just like NASCAR, no one wants to just watch cars go in circles, they want to see a twisted heap of scrapmetal on the track after a huge wreck.
Once the observer actually gets what they want, they yell and cheer and rave about how good of a show it was. Unfortunately on a rare occasion it goes just a little too far and someone loses their life. Do they ban stock-car racing after Earnhardt died in 2001? Nope, they took a couple weeks off to grieve, test the equipment, and implement some new safety measures, then were right back in it a short time later.
But like the others have said, it's the nature of the beast. You whether want to swim with 12,000 LB natural predators or drive 800 HP cars at 175mph, you have to live with that risk. Yes, safety measures are constantly being improved, but I don't think we're even close to being 100% safe.