After the end of the war the Japanese were fascinated with MacArthur, who was in many ways the public face and public persona of America in Japan during the military occupation. This is partly due to the Japanese history of an ostensibly unitary government, in that they saw the Supreme Allied Commander as being personally and solely responsible for victory, but MacArthur, notorious for his tremendous ego, certainly did nothing to disabuse them of that notion, and certainly did a lot to re-form (and reform) the Japanese government to be less opaque and autocratic. However, by late 1950 MacArthur's fame and influence seem to have gone to his head, and he made some rather choice remarks about Truman's conduct of the Korean War and foreign policy which cost him his job, and a little later some rather choice remarks about the Japanese that cost him public esteem in that country.

Source: John W. Dower's Embracing Defeat: Japan in the Wake of World War II. Dower tends to think MacArthur's remarks about the Japanese were fair and well-intentioned but poorly expressed; I personally wouldn't give him the benefit of the doubt.