Sometimes "revisionist" also means "finding out what we didn't know at the time."

For instance, Japan was indeed trying to surrender:

"American intelligence had broken the Japanese codes, knew the Japanese government was trying to negotiate surrender through Moscow, and had long advised that the expected early August Russian declaration of war, along with assurances that Japan’s emperor would be allowed to stay as a figurehead, would bring surrender long before the first step in a November US invasion could begin."

That, and Eisenhower was against dropping the bomb. He knew it wasn't necessary.

Source: https://www.thenation.com/article/world/why-the-us-really-bombed-hiroshima/