We have a moral obligation to advocate for the victims of Hiroshima and Nagasaki nuclear bomb attack, as much as we have the obligation to advocate for the Rape of Nanking. Nazi German War Crimes does NOT give USSR and Allied atrocities against German civilians any justification. Because war and atrocity can happen to anyone. This is why we as normal common civilians are all in together with this.
You think this is just about your little pride, you think this is just about us wanting an apology. Don't fool yourself! Japanese apologies and repentance isn't worth anything now. With Japan as toothless as she already is, if she is any more spineless, it would only make her an even easier target for the like Trump to swindle strategic concessions from. Japanese concessions to the US is NOT something China, Russia, nor Europe would want now.
If you truly want a world where people can forget and forgive the past wrongs and transgressions, start with true reconciliation, start with finding common ground and common interest. Putting war criminals in their due place is a common interest, because it also helps to protects the Japanese from becoming the victims of future war crimes, to a certain degree, especially when Japan has pretty much conditioned herself to be a peaceful nation in the last 75 years.
In the long run, it is more in the interest of future Japanese to be tough and have higher standard towards War Crimes, than in the interest of future Chinese, Russians and Americans. Think hard about this.