Well it depends on the way you look at it. Japan wants to surrender but not have the emperor prosecuted. America says no, must be unconditional. America drops two nukes, USSR invades Manchuria, breaking neutrality. Japan surrenders unconditionally. America agrees, but says they won't prosecute the emperor.
So in one regard it was needless. On the other hand, Japan had commited such barbaric and vile acts, it could be coldly suggested they needed to be bombed back to civility, and taught a lesson future generations wouldn't forget. There'd been two colossal, total wars in the past twenty five years, and it was hoped the bomb would make all other wars impossible. Twenty years later, Japan is a thriving country with a healthy blend of eastern and western culture, with western economics, social mobility, suffrage, and hasn't thought about committing disgusting war crimes to south east asia or china again. Back then, the damage radiation could do was relatively unknown and...
...you know, fuck this. I'm here to talk about Lindsay Ellis.