Not just the atom bombs but also firebombing of Tokyo ( http://en.wikipedia.org/wiki/Bombing_of_Tokyo
) where the number of casualties on a single raid was "greater than Dresden, Hiroshima, or Nagasaki as single events."
To make this more concrete:
"One American pilot wrote in his diary, "Suddenly, way off at 2 o'clock, I saw a glow on the horizon like the sun rising or maybe the moon. The whole city of Tokyo was below us stretching from wingtip to wingtip, ablaze in one enormous fire with yet more fountains of flame pouring down from the B-29s. The black smoke billowed up thousands of feet, causing powerful thermal currents that buffeted our plane severely, bringing with it the horrible smell of burning flesh.""
I find it incredible and unbelievable that the endgame of WWII in Japan didn't have a profound impact on both Ueshibas and their students at the time.