I'm afraid there are too many pro-"but mah guns!" folk with the fantasy of being just the John Rambo-esque hero needed to stop the massacre-in-progress with their own gun, for them to want to take any steps to possibly make your much-more-desirable scenario happen, though. =/
It's as though the "we just need more good guys with guns, but absolutely DO NOT try to regulate them more!!!" crowd is saying: Yeah, just give me a bigger gun than the bad guy who shoots up schools, and he'll be stopped, no problem! Sure a child or two or three will quite likely be sacrificed before I can identify the shooter and react properly with my own weapon, but that's just the price we have to pay to keep guns in everyone's hands, just like the good Lord intended! If it means making it any harder or more inconvenient for me to feel safe by owning a gun (because clearly that is the only way I can ever be safe), then I don't want preventative measures! Only reactive!