Agreed. Training will definitely enhance your ability to respond well in different circumstances, but I don't think it is necessary. Desirable, but not required.
I think the comment by spetznaz at #29 above pretty much summed up where I'm at on this,
Clearly it isnt necessary. However, youre nuts to carry in public w/o it. Really, think about it, youre carrying a deadly weapon w/ no idea what to expect, how to respond, how to deploy, nothing. Your training to that point is all from Hollywood. The prime reason CCW holders SEEM to do well is criminals are cowards and dont want to be shot. Now insert a motivated terrorism who cares little if he dies. Youre going to lose! Its actually troubling the number here who believe only a weapon is required to prevail.