There's an excellent book that covers this topic called Embracing Defeat by John Dower.

In a nutshell, success was achieved due to complete Japanese submission to an occupying authority that viewed Japan more as a useful ally in the emerging Cold War than as an enemy to be punished. While the Japanese themselves greatly desired a way of life that was similar to the Americans and were eager students in learning how to accomplish that.

I would also say that compared to their other potential occupiers (China, Russia, Korea, etc), the Japanese felt they were lucky to be under the occupation of the comparatively merciful Americans who wanted to build up Japan rather than grind it down and who also wanted to keep Japan whole rather than divided up as had been done to Germany.

In the end, the Japanese had every reason to go along with the American program and very few reasons not to.