Yes Harris was cold blooded man, but he had a job to do, to wage war against the enemy with all that he could muster. as others have pointed out, for a long time at the beginning of the War, the Bomber Offensive was the only means we had of striking back at the enemy, and helping our Allies, in taking some of the heat off of them.
War is a dirty business, and people get killed, on both sides, Military or Civilian..Area bombing was a blunt tool to get at Hitler, but precision bombing, even in daylight with a Norden bombsight, was just not accurate enough.
I am also sure that if the Manhattan Project had come to fruition 6 months earlier, Berlin would have been the recipient of Little Boy and maybe Dresden would have got Fat Man...maybe that would have convinced the Nazis to pack it in...What would we have made of Harris then?