Yes you are correct about McNamara. He was our own worst enemy.
OTH. The changes in bombing strategy mostly had to do with the fact that almost all of Japan lived in matchstick houses. There were very few masonry/brick structures. LeMay rightly guessed that it wouldn’t take much to torch the place.
He was right.
Something to keep in mind, If you look at the total world war II casulties including civilians:
only 4 percent of the total military deaths were Axis civilians. 58 percent of the total were allied civilians.
Soviets lost close to 24 million and China lost close to 20 million. Japan lost about 2.5 million.
Most of the Axis civilian casulties (about 3:1) were between Germany and the Soviet Union. Japan had barely more civilian casulties than Romania.
I think that pretty much says it all. For all the handwringing over the Americans and their conduct in the war - I think the numbers are sobering. They did not target civilians whereas their enemies were all too happy to do so.