@sweet tea, I absolutely agree that there are those who are irresponsible with their permits. Specifically, as you put it, novices. Typically a middle aged woman who shoots her gun one time for the permit and then probably never goes back to the range. This is however, a very rare thing. Most people who are comfortable enough with a firearm to carry it daily have already have a large amount of experience and maintain proficiency because they simply enjoy shooting guns.
Even an absolute novice could save lives in a shooting spree event. In both the Clackamas mall shooting and the most recent CO HS shootings, the presence of an armed individual caused the shooter to commit suicide. Obviously not something to rely upon, just my two cents.