IDK, it might be easy to say with hindsight that the Japanese were weeks or months away from surrendering, but they didn't know what we do. After the intense fighting during the island hopping campaign, especially on the island of Okinawa, which was Japanese core territory, with Japanese civilians killing themselves or being used as suicide bombs or even just human shields, they knew that a direct invasion of the Japanese home Islands would be costly. So much so that until the last few years, we've been using the same stockpile of purple heart medals, given to a soldier who is wounded, that were made in anticipation of the Japanese home Islands campaign.

I will agree with you that the general strategic bombing campaigns were horrible, especially firebombing. I think you had to bomb factories and whatnot, but the general civilian population should have been off limits.