The trouble is in war, innocent blood will be shed. The bombing of cities was not a good tactic (other than being immoral). For instance, in Germany it was thought that bombing and killing the factory workers would slow production. It didn't. Dresden and Hiroshima are part of the reasons that we don't do carpet bombing of cities anymore.
But in 1945 the Allied command had two or three choices. First was ground invasion, which would have devastated Japan and realistically cost a million lives (probably more). Second was a blockade. Which had already failed to incapacitate Japan, and would have had to starve a good portion of the population to death before they surrendered. The third was the atomic bomb.
No good choices there. No way to not kill innocents, no way to just go home and say "Game over, you guys lost." War is like that. If we pulled back and just said "Oh well", Japan would have rebuilt and attacked.
The choices for targets always confused me, and I do not agree with them, but to be honest I can't think of a way that would have got Japan to surrender cheaply.
The problem with looking at alternatives to something that has already happened is twofold: for one thing, we can never actually know how the alternatives would have turned out; and secondly, you often don't grasp the consequences of what actually DID happen.
For instance, consider this: WWII marked a moral turning point in that not just the "bad guys," but even the "good guys" carried out massive and strategically deliberately attacks against civilian populations.
In the aftermath, during the U.S. Occupation of Japan under General Douglas MacArthur, Japan passed a law entitled “the Eugenic Protection Act of 1948,” encouraging voluntary sterilization as a public health measure. (In addition, reportedly some 275,000 Japanese were involuntarily sterilized.) Also in the wake of Hiroshima/Nagasaki Japanese law was changed to permit abortion for most genetic or chromosomal disorders or congenital malformations.
Every such law is not only policy, but precedent. Heretofore in most nations considered criminal and in many, unthinkable, abortion became newly associated not with crime but with public health. So the surgical killing and trashing of unborn babies picked up a certain undeserved respectability, and began its long march toward universal acceptance.
Or maybe not such a long march. By 1962, the American Law Institute published its "Model Penal Code" de-criminalizing abortion for certain hard cases. Within 20 years of the Japanese abortion law, abortion law was liberalized in Colorado and California. (Some so-called "ethicists" had picked up on the WWII-vintage idea that you can intentionally exterminate the innocent if you have a really good reason!) In 1970, New York (followed by Alaska, Hawaii and Washington) introduced the first laws to allow abortion "on demand."
Then came Roe vs Wade. Then over a period of 30 years, 1/4 to 1/3 of all babies conceived in the United States of America were killed. That comes to approximately 50,000,000 dead.
Is this one of the long-term consequences of Hiroshima/Nagasaki? I think the argument could be made. Once you accept in principle that the prohibition against the intentional shedding of innocent blood can be set aside in favor of our own better judgment, the consequences can play out across a range of situations. And if the killing of 1/3 of the children in America is not a consequence of the "new morality" of targeting the innocent as in Hiroshima/Nagasaki, it may be its punishment.
Was there any talk of doing a demonstration bombing? Like blowing the top off that sacred mountain?