Well no, Japan didn't get invaded, so millions of lives wasn't lost. Japan wasn't burned down from the inside out like Germany where almost every town and cities was rubbles and it took Germany a while to recover (1960).
Because Japan was spared from this (somewhat), they didn't loose a tremendous amount of people. At the same time, they were quick to recover from their losses and they focus on economic rather than defense. (the military is banned). Like Costa Rica, who also banned their arm forces and started to focus on themselves, they ended up being a major economic powerhouse.
I believe that the bombings were totally justified and that we should have also bombed China afterwards, only because they would end up being one of the reasons for the economic downfall in the US today, which no one knew back then, but still could have anticipated it.
The cold war didn't negatively impact the US, on the contrary it allowed the US to bolster its military as well as become a leader in foreign intelligence. On the other hand, China's "artificial" inflation and deflation of its currency allows it to make trillions of dollars in profits by keeping the products made within it exceedingly cheap to produce.