But the Japanese were not going any where. They were trapped on their island. We could have waited a year...two for an unconditional surrender. McArthur was the one that was able to transform that situation and help them save face and make the a valuable partner for the next 60 years.
Wait for what? The Russians to invade from the west. A full scale invasion was already planned. Waiting was not an option, because of the Ruskies.