Why Aren't Hiroshima and Nagasaki War Crimes?

Because we won. The whole "war crime" business is just how we justify in today's oh-so-sophisticated society the ancient custom of the winners imprisoning and executing the leaders of the losing side.

I reject the premise and refuse to feel guilt for my ancestors doing what was necessary to win a total war.

Because the allies won. Plus the whole BS used to deny that Japan was basically begging to surrender (just not unconditionally so they save some face). Similar to the BS used to deny the fact that Japan was provoked into Pearl Harbor, after having been strangled economically for months.