Check out the conquests of Caesar and Alexander the Great.
They preferred settling among the local populace, including forced marriages/rape. It's harder to rebel when the invaders are your neighbours or even your fathers.
Cynically speaking, that's better than just evaporating innocents.
1. The Japanese would not have capitulated until much more suffering would have taken place.
2. Negotiations with Russia were going on over the division of Germany and the atomic weapon blasts tempered Stalin's resolve that he had the more effective fighting force.
3. Innocents die in war. Whether from gas chambers or fire bombings or atomic bombs. If we want to stop this from happening then we need to reduce the frequency of war. Especially total war. Or do you really expect the US to send in it's bachelors to rape defenceless Japanese prisoners for decades? In the time of Alexander the great less than 3% of the population was used in fighting forces because manpower was required to keep up the food supply. It was a completely different era with a completely different set of circumstances that we don't even fully understand because we don't have the same level of records about it.
It was an answer to a ludicrous question... I certainly don't endorse the approach of Alexander the Great :)
Mainly, I feel the phrase "total war" is a hyperbolic, "binary" phrase that doesn't allow for meaningful, nuanced debate. That's all I was trying to counteract.
They preferred settling among the local populace, including forced marriages/rape. It's harder to rebel when the invaders are your neighbours or even your fathers.
Cynically speaking, that's better than just evaporating innocents.