If you're intent upon genocide, sure. Otherwise, the point of war is to make your enemy tractable to your dictates until he's no longer your enemy.
I guess firebombing Berlin and obliterating two cities in Japan didn't work out so well either.
Neither ended the resistance of the governments we were at war with, as keeping hold of the reins of power superseded any concerns about the suffering of their civilian populations. Do you expect the Taleban would be any different?