I defiantly agree that it was bombing of Ruhr factories and German infrastructure that had most of the effect and can be justified both economically and probably morally. Much of the criticism of the campaigns I think usually are both the early city bombings in particular Berlin (I guess you could argue that something like Hamburg at least was somewhat cost efficient but the bombings further east was a huge waste) and the really late war bombing. This is a pretty large share of all missions though.
As for your math exercise extrapolating is always dangerous and your numbers while significant I would guess are less than the British bombing commands share of the UK military budget?
As for your math exercise extrapolating is always dangerous and your numbers while significant I would guess are less than the British bombing commands share of the UK military budget?