Earlier quoted context omitted.
A different perspective, not trying to justify killing civilians. No matter which way a leader comes to power, the population pays the taxes and the ultimate tolls. This means that when we are on the inside, in the country, we can't be more or less complacent with a bad dictator than a bad elected leader, we always pay the price for what they do. It's always our problem.
Back-channel peace negotiations had been taking place for quite a while before the war ended. There was a large faction in the Japanese leadership that wanted to end the war, because it was widely understood to be unwinnable. The offer was a negotiated surrender that would end hostilities with some face-saving concessions - specifically for the Emperor. There isn't a perfect historic record of the negotiations, but i…
The Japanese leaders didn't deserve them after what they'd did, and it really would have changed the entire post-war dynamic between Japan and other countries, and even more importantly, between the Japanese government and its own people.
Here's one term from the Potsdam Declaration, which the Japanese rejected: "The Japanese Government shall remove all obstacles to the revival and strengthening of democratic tendencies among the Japanese people. Freedom of speech, of religion, and of thought, as well as respect for the fundamental human rights shall be established."
It's not unreasonable to say that had the Allies not continued prosecuting the war and pushing for unconditional surrender that Japan might not have ended up with a democratic government at all. It would have been much worse if the emperor and military figures had stayed in charge, and could have easily led to more repeats of wars of Japanese imperialism.
So yeah, I think it's important to look at it holistically and see what the actual long-term outcome after the war was (which was about as ideal as was possible), vs. what would've happened had we just ended the war as quickly as possible to minimize casualties but without getting wholesale reforms in the Japanese form of government.