Good point. But even if we were talking about full auto AK-47s in the hands of those intending to do harm, as the North Hollywood shootout shows, these tools aren't as lethal or deadly as the media would have you believe. Expending thousands of rounds, the perps didn't kill anyone they hit. When the submachine gun wielding SWAT team had to steal(borrow? illegally transfer?) civilian AR-15s from a gun shop to penetrate the perp's body armor, they finally stopped the robbers. One perp committed suicide with a handgun rather than surrender, and the other died much later from his wounds as the perp was last in line to receive medical treatment from the EMTs. His family tried to sue for the delayed medical treatment. With quicker treatment he would probably have survived. If the cops had used a decent centerfire hunting rifle, the deaths would have been much quicker and certain.
Volume of fire is a consideration for military engagements to control troop movement or suppress fire where pinned down combatants can then be targeted with artillery or air support. Outside of military engagements volume of fire that misses is just turning money into noise.