I think the area bombing falls into the category of stuff which on an individual action level was a horrendous waste of life on both sides, but on a strategic level was essential to the Allied victory, because British bombing raids on German cities provoked Hitler into focusing German efforts on bombing British cities, which was considerably less useful to the Germans than the military targets they were hitting before, in the context of Britain desperately trying to avoid the Germans establishing the degree of air superiority that would allow an invasion of the British Isles.
A corollary of this is that the sacrifices made on bombing raids later in the war, including by US forces, were a lot less relevant. US bombing strategy was typically more targeted towards military assets than UK bombing though
(There is of course also the massive can of worms of how necessary the atomic bombs were: obviously unlike other bombings they actually did bring about immediate capitulation, but in the context that parts of Japanese High Command were opening tentative discussions in the full awareness that they were losing the war, and possibility the US might have been able to offer its surprisingly reasonable ultimate terms instead of unconditional surrender)
(this op-ed is the first thing that popped up on a quick google but it has been covered much more thoroughly elsewhere - the short of it is that having a city bombed to oblivion wasn't actually a terribly novel thing for Japan at this stage of the war, whereas the Soviet invasion of Manchuria was a Big Deal)
A corollary of this is that the sacrifices made on bombing raids later in the war, including by US forces, were a lot less relevant. US bombing strategy was typically more targeted towards military assets than UK bombing though
(There is of course also the massive can of worms of how necessary the atomic bombs were: obviously unlike other bombings they actually did bring about immediate capitulation, but in the context that parts of Japanese High Command were opening tentative discussions in the full awareness that they were losing the war, and possibility the US might have been able to offer its surprisingly reasonable ultimate terms instead of unconditional surrender)