The nuking of Hiroshima and Nagasaki is honestly one of the single most effectively altruistic actions in all of human history.
By helping persuade the Japanese to surrender (they were open to doing that with preconditions, but that was hilariously at odds with the military balance by mid-1945), the Americans helped make the world a much better place.
(1) Military death estimates for the invasion of Japan ran into the hundreds of thousands, which would have been equivalent to America’s military deaths for the entirety of World War II. The US was under no obligation to sacrifice masses of its troops to spare citizens of a country that had underhandedly initiated war against them.
People who are against nuking the Japanese hate Americans.
(2) The USSR would have lost tens of thousands of soldiers occupying Hokkaido and perhaps northern Honshu (only to lose said Hokkaido People’s Republic in c.1991 anyway).
People who are against nuking the Japanese hate Russians.
(3) Japanese troops were still occupying Korea, Vietnam, Indonesia, and large parts of China. Japanese occupation was not nice. A timely Japanese surrender saved many Allied troops and third country civilians.
People who are against nuking the Japanese hate Chinese and other East Asians.
(4) Previous fire bombings killed more Japanese than the two atomic bombs.
So what even makes nukes so revolting to many people? They’re just more efficient at their job.
(5) An Allied invasion of the home islands would have killed millions of Japanese civilians, or an order of magnitude more than were killed by the atomic bombs.
People who are against nuking the Japanese hate the Japanese.
(6) Showboating American nuclear capabilities to Stalin made the Soviet dictator warier of taking more liberties with the Western Allies in Europe. Since the postwar USSR was a depopulated wreck, while the much wealthier and reinvigorated US was accumulating dozens of nukes per year (thousands from the late 1940s), this must have reduced the risks of a Russian atomic genocide, which quite a few American generals were calling for.
People are who against nuking the Japanese really, really hate Russians.
Moreover, all of this truly psychopathic hatred comes wrapped up in supercilious moralization.
But I for one would like to take a moment of my day to thank the brave American aviators who nuked the Japanese. Glory to Atom!
PS. It is now commonly accepted that the Soviet invasion of Manchuria – or more precisely, the Japanese losing any hopes of the USSR intermediating a more favorable peace with the Americans – played no less a significant role in prompting the Japanese to accept unconditional surrender. However, the nuclear bombing did help things along – Japan’s civilian leaders were truly demoralized by it – and in any case, the American perspective that nukes could force the Japanese to peace was a perfect reasonable one.