An interesting perspective summarized here [0] is that the bombings were not just unnecessary to end the war and were conducted as a show of force to the Soviets. They were conducted in an attempt to end the war ASAP, before a planned Soviet ground invasion of Japan so that the US wouldn't have to share control over post-war Japan with the Soviets.
[0] https://www.globalresearch.ca/the-real-reason-america-used-n...