Yet in the final months of the war, with the enemy prostrate and paralyzed on his home islands, was there any real justification for the hellish firebombing that took hundreds of thousands of civilian lives without achieving anything of military significance? Or was that bombing just a sad indication of how Japanese brutality sometimes made America no less barbaric?
Umm, yes. As one of his commenters points out, it took firebombing and two atomic blasts before Japan conceded defeat--and that only because the emperor intervened. Churchill and Truman knew that victory for us meant the complete and utter defeat of them. See also Sherman, War is hell. One could argue that neither the Israelis in Lebanon nor the US in Iraq are using enough force.
Which is better for the civilian population: A short, brutal, devastating war from which a clear victor emerges? Or years, perhaps decades, of chronic conflict during which only dozens of people are killed on a daily basis?