What are you talking about?
> Negotiating with irrational actors is risky
They never even tried it.
I'll make this simple. The only justification for the fire bombings and nuclear bombings that has any possible merit is that they were necessary to end the war. However, the US never even tried to negotiate, nor did they try to communicate to the Japanese that they would be willing to allow the Emperor to remain nominally in power. They could have used that to end the war far sooner.
So how could the bombings possibly be necessary to end the war when the war might have been ended by other means? I'm sure you'll say that that wouldn't have worked, but how would you know? The lack of any attempt shows that the US wasn't interested in ending the war: they wanted revenge, and therefore the bombings were not justified.