“ The allies collectively had agreed to demand unconditional surrender, the death cult that was the Japanese militarists was always going to force something bloody and awful to end their rule.”
Bloody and awful had already been tried, about 60 times. The US Air Force was running out of cities to bomb, yet the Japanese military showed no concern, either in their public actions or their private communications discovered later. They didn’t even bother to call a meeting to discuss surrender after the first nuclear bombing, but they did after Russia joined. The nukes didn’t change the strategic situation one bit, Russian entry did. Militarily it meant that huge chunks of their empire was going to be conquered whether they wanted to surrender to the USA or not. Secondly there was no chance of the USSR becoming an intermediary and helping to get a better peace.
In the end not only did the nuclear attacks not work and were clearly not going to work. Why would one plane devastating a city scare you when 500 planes could do the same thing, and there is a practically limitless supply of enemy planes?