Both Germany and Japan were cohesive relatively united countries with one main religion. Also McArthur really understood the Japanese mentality and other Europeans understood German. Totally unlike the religously split, held together by terror mess in Iraq.
Many of the trouble spots in the world are the legacy of the colonial period when European colonial powers divided and mixed together warring factions to rule more easily. There ought to be an international conference to redraw the lines, with some system to redistribute the goodies, especially those underground to the fair benefit of the resulting countries.
Germany was wracked with religious war during the 17th century. 30 years of it... Catholics v. Protestants.