It was so near to the end of the war and the bomber crews could see what they were doing - especially the second wave that caught out so many of the young firefighters.
Just to remind you that it was Britain that declared war and it was Churchill's pressure to start bombing civilian cities - the Germans were not initially intentionally targeting civil areas but Hitler was under political pressure to retaliate in kind. The now known deliberate "de-housing" strategy carried out by the RAF was indeed a war crime - it was areas of the highest density housing in Dresden that were the focus.
You need to understand whose pocket Churchill was in and what was the particular significance of Dresden to them.
Why the Polish government did not accept Germany's generous compensation for letting the Danzig corridor go (re-uniting East Prussia with the rest of Germany) is hard to understand - perhaps it was under pressure from elsewhere to trigger that war.