It is just a dog and pony show and the intended audience isn't for us but for Japanese citizens. Nuking civilians is never justifiable but between another million of Americans and allies troops that would need to die in order to take Japan. I think it is a necessary evil. In addition, as much as these politicians laying flowers today, most of them won't hesitate to do it again if their rivals can't retaliate in kind.
But for many mainland Chinese, I do believe they would choose not to nuke Japan during WW2 so that they could seek revenge and made Japanese paid for their crimes. As much as some people claimed that it is time to forgive and forget, Japanese never paid for their crimes and compare with the suffer that Asians and especially China by the hands of Japan, Japanese got away too easy with the nuke. That's why I never understand why they have the audacity to play victims. But as long as you are the ally of the West, you probably can get away with anything.