Dresden and Hamburg were both industrial cities and therefore were targeted to stop the production of war goods.
With the jews being put into ovens as well as Americans, Pols, etc, they were illegally held, were not a threat, and were tortured and incinerated for no other purpose than to make them suffer. The jews, pols and others that were not in the military were non combantants and posed very little threat, and even if you were a pow, you still pose little threat at that point. And no in this world warrants that kind of hell.