If the invasion of Japan only cost 10,000 allied lives, do you think the mothers and fathers, sons and daughters of those who died would have appreciated sparing the lives of those in an agressor country when we had spent so much money developing a weapon that would end the war with no US casualities? My grandfather, on the command communications ship USS Ancon, could easily have been one of those, after having come under fire (heavy fire at times) for five invasions from Torch to Okinawa, with Normandy in between.
And don't overlook the rampant starvation that was starting to sweep Japan at the time, and continued to kill months after the war ended. Sakai talks about it in his book, and there is even a statue to an American naval base commander who opened the garbage dump to the local population. A longer war would have resulted in death and suffering for the Japanses people far beyond the two bombings, for many reasons.
The war ended, the American soldiers and sailors (and those from the other allied nations) got to return to being civilians after haveing been fored to fight in a war brough on by others, and the world moved on.
Charon