I believe Truman’s analysis was right, that taking the ground war from Okinawa to the main Japanese islands would have seen more unacceptable levels of military deaths on both sides as well as more civilian deaths as well. Ending the war sooner was better than ending it later.
Full disclosure: I am not saying the next thing to support what the militaristic Japanese leaders did; not at all.
However, in the context of the times, turn of the century, it is not hard to understand, looking around Asia then, that many Asiana saw that “empires” ruled the world, even in Asia, but none were Asian, until Japan.
Howver again. modern, post WWII Japan, has learned now that an empire was not needed to be prosperous and successful. It could have had a peaceful “Asian commenwealth” instead of an empire, if it had had different leaders.
Dropping the bombs saved Japan from a Civil War, as happened in Korea. The Soviets would have occupied the North, and would have made their move to take over the whole country.