From what I've heard, much industrial production in support of the Japanese war effort was distributed among the residential neighborhoods, so I don't know whether maximizing civilian casualties was the intent or not. Nevertheless, I doubt that every bombing target in that war was justified morally and militarily.
It's awfully easy to sit here in the comfort of our computer rooms 60 years later and second guess people who were trying to deal with a very desperate situation world wide. World War II was very much a war against civilians. Those who defend trying to maximize civilian casualties today are in effect arguing for a return to the bad old days.