As bad as it is, casualties have to be assumed when events like that take place. What I am trying to say is, if 10 people around him were carrying, it takes them a second or so to understand what’s happening, find the guy shooting, reach, upholster, cock and return fire. By that time the gunman could pop off a bunch of rounds, probably hitting targets.
Self defense is never going to be an all or nothing success or fail by definition. What it will do is help keep the guy from just dropping empty clips, reloading and getting off a box of ammo at helpless people. If people are armed with a weapon, and a law, it can only help.
And the point of missing your target if you are legally carrying. Keep it simple again. Make the test a test, not a paperwork lesson and a hook up from a judge to allow you to carry on your person. Form the laws to give someone with the skill and correct mentality to carry out safe self defense tactics the ability to do so. If you miss and take someone else out, you face charges. It’s your decision when shit hits the fan. If you have a weapon, and the situation is too hard for you to defend yourself and others safely, don’t fire. If it’s a risk you are willing to take, fire. simple as that.