From a modern perspective it would have been a war crime. I don't think you can argue this. The discussion isn't mostly about if it was a war crime or not, but about its reception. Basically, if the bombing of Dresden wouldn't be used by revisionists, apologists and Neonazis for demonstrating how bad the Allies were, we could have a more nuanced and neutral discussion.

This topic isn't really about history per se, but rather about morals. Is it okay to dish out punishment? Is it okay to give the same treatment as the Allies recieved?

How the argument is established often shifts the perspective to make Germans seem as victims, and leave out the actual victims. There is a famous quote from a holocaust surivor who said that he saw the burning of Dresden from the KZ Theresienstadt and thought that liberation couldn't be far off.

Also it is a good example of what total war actually means. It means that there isn't really a division between military and civilian population. One feeds the others efforts. It is about the reproductive force of the whole state. Without the efforts of the war economy in Germany the Wehrmacht couldn't advance. The Germans wanted total war, and they got it.