The Polish did bring up WWII at the European Summit in June didnt it? They said their vote should be increased disproportionately to their population since many Polish had been killed by the Germans in WWII.
The reason Japans neighbours keep bringing up the issue is because anti-Japan is their regimes' raison d'etre. Take a look at the history textbooks used in China and Korea for example; they are totally one-sided, of course with some truth but also with a lot of lies, and deliberately edited to nurture hatred towards Japan in many generations to come. No wonder even if they keep bringing up the issue. Another reason could be that they tend to look down upon Japan as being morally inferior and barbaristic for historical reasons, but the fact now is that that Japan is still more advanced than they are. The situation is different in Western Europe where the countries' stage of development is roughly the same.
And for apology in action, Japan concluded the basic treaty with Korea in 1965 and extended huge money to them for Japan at that time, in addition to renouncing all assets in Korea belonging to the Japanese. Unlike Germany, Japan paid the money to the state of Korea upon Korean Government's request. Has any other country extended such generosity towards former part of its own or its former colony? But the shame is that this fact was hidden by the Korean government against Korean people until recently.
And unlike Germany again, Japan paid war compensation to the countries it occupied at WWII, including Indonesia and the Philippines. Correct me if i am wrong, but I understand that Germany compensated for holocaust but not for WWII itself. You better not believe China and Korea's claims against Japan literally.