Read the book "Dresden" by Frederick Taylor.
It was only written in the last 5 years or so. He makes many of the same points that Marshall de Bruhl made.
Though Germany was on the ropes, the Allies felt that Dresden still possessed a significant military-industrial capacity. The Allies also wanted to destroy the rail lines leading in and out of Dresden to keep the Germans from transferring troops from one front to the other.
I think that an argument could be made that the use of incendiary bombs was over-kill (no pun intended). The use of high explosives to accomplish the destruction of the rail lines and smaller factories should have been enough.
But then again, if you were a dead civilian, you probably didn't care whether you were killed by fire or bomb blast.
With today's technology it would have been enough, but back then more than half the bombs dropped didn't land anywhere near their targets. HE had to be close to be effective, but with incendiaries a lot of infrastructure could be destroyed even if they missed.
Well, we were after un-conditional surender. This is how you get it. The pussies of the world dont win wars, Men do.