What would the US have to gain from such attempts anyway..?
I don't think that, what other countries have done, has anything to do with Japan's situation. Nations act hypocritical anyway..
If that "trouble" between China, Japan and Korea would come to pass, the US would have to gain: the chance to "intervene" (aka invade, blow up and torture) those countries, play hero and savior and while at the same time carressing their "reputation" of being world police & savior, they, as that "savior" have, of course, every right to take whatever comes their way. Riches, technology, people...
No, you are right, what other countries have done doesn't make Japan better but there are countries that have done too much to qualify to point at others. As mentioned before: black slaves, butchered Natives, molten Japanese, and hey, when they invaded Germany, they killed more civilians than "bad guys". No, wait a sec, they did that whereever they went! Silly me!
As for recent reasons to apologize, has anything more than "Sorry but we do this for the sake of world peace (the word "world" is actually an American English synonym for "USA") so ****" ever come concerning Guantanamo?
If Belgium wasn't so small and stuff, we'd be at gun point too for not apologizing for Marc Dutroux... When the US need something, they take it by taking a menacing posture, trying to make it look like diplomacy and when that don't work - BOOM
The fear of that "boom" noise is pretty much the main reason why the US manage to bend so many countries their way. Ruling through fear and violence may be an effective way of ruling indeed, but, allow me to be naieve, how do they fool their conscience so well with all the "God bless" and stuff...
Japan should apologize, but not only Japan and not on orders of the US who should start writing a looooooooooong list of apologies too and practice some sincerity while they're at it. What do the US think they are, the Olymp?
As long as the countries bothered by Japan don't ask for an apology themselves, the not re-al-ly that much concerned US might as well shut it.
In short, it's not a matter of "is Japan that bad" but of "are the US any better". And when you got that much dirt under your own carpet, don't tell others to clean theirs. Japan may have alot of dirt under its carpet, but we also don't see Japan policing the world like an army of saints.