If it hadn't been there and then, it would have been somewhere else some time later, maybe deemed more justified, or maybe less. I don't think people would take the bomb as seriously as it is taken now if it had never hit a largely civilian target.
It did what it had to do for a quick capitulation of Japan.
WWII has never shied away from civilian deaths, it has around the same or more civilian than military casualties, and Japan's civilian ones are 1%-ish of the total.







