On the Allied Destruction of Hamburg, Dresden, Tokyo, Hiroshima, and Nagasaki

With the possible exception of Hamburg, each of these incinerations (and, yes, I'm using my words carefully) took place at the tail-end of the war when the conclusion of it wasn't even remotely in doubt.......Which leads me to query here; if the targeting of civilians is a war crime in the worst of circumstances, would not these much more gratuitous and vengeful acts be seen in an even nastier light? One could make the case, in my opinion.