The Japanese refused to surrender. There was no question that they had lost the war. We firebombed every major Japanese city and still they refused to surrender. It was only after we had dropped our SECOND atomic bomb with the threat of endless more that they finally surrendered.
The Japanese were much like the muslim fanatics that we are at war with today. Now Japan is an ally. There is a lot to be said for bombing a fanatic culture into oblivion.
Little was left standing in many homes except the drill presses that were used to produce weapons for the military. Cottage industry.
It's the difference between bombing someone "back the stone-age", or bombing them "into the present."