It was also a response to the horrors of world war 1, where armies faced each other in open fields and the conflict dragged on for years without lines changing

It was also a response to the horrors of world war 1, where armies faced each other in open fields and the conflict dragged on for years without lines changing much. The reasoning was that ending the war quickly by completely destroying the enemy's capacity and will to continue fighting was better than letting it drag on and become a meat grinder, even if that meant bombing civilians and civilian industry. Obviously this didn't work since WWII was both longer and more deadly than WWI but that was the thinking.