Lots of opinion and moral argument here, but its no use trying to judge the events of 60 years ago by today's standards. The German Luftwaffe initiated the black art of strategic bombing in Spain, took it further in eastern europe and refined it over Britain. Coventry actually seems to have been an experiment to measure the accuracy of their blind bombing techniques.
Later on Bomber Command and the US Army Air Force went on to write the handbook of strategic bombing and they were breaking new ground. Its no use wringing our hands over it 60 years later. In the sixties I was proud to serve in Bomber Command and I recall that we and the USAF seriously expected to convert vast areas of the USSR into glass if the Russian army put even so much as a single private's toe over an invisible line drawn in West Germany. I'm not ashamed of that at all, its just the way it was.
Leave Arthur Harris alone and lets all go down the pub for a pint together.