I think it was a necessary evil that had to be done, if anyone thinks Japan was going to surrender regardless if the entire world declared war on them, is living in some other world, it would literally fight till the last man. It needed such heavy shock and awe to coerce it into surrender.
And its not the first time a city was destroyed, like mentioned before Tokyo was flattened by conventional means and it didn't even phase the Japs
This is Tokyo, not Nagasaki or Hiroshima after the bombing raid.
Hamburg was also destroyed in German with more casualties and fatalities. Don't see anyone crying over that here either.
Face it Japan at that time was a major evil piece of shit and it was not going to back down.