you know how japan has a nigh pacifist constitution?
That isn't something the united states really imposed on Japan or even wanted. That was the Japanese people just being real sick of the military being out of control.
More like a pissed-off US imposed it, then said "uh, take back?" when the Korean War began, and the Japanese said "lol no."
Now as for the actual argument: that Hirohito was an ignorant puppet is nonsense. He knew what was going on, he gave his full acquiesence to the broader ideas if not some of the gorier details, and he himself realized that there was a good chance he was going to be killed at worst or forced to abdicate in favor of one of his younger brothers at best. I generally think the Tokyo and Nuremberg trials are bullshit and that the ringleaders of both countries should have been straight shot. And if any one person in Japan deserved to be shot, it probably was Hirohito (and Yamashita should have been allowed to live because that was straight bullshit what happened to him.)
The Japanese people would have preferred keeping the throne as an institution compared to ending it altogether, but if the US had really insisted on it, they could have destroyed the throne. MacArthur was the one who was extremely gung-ho about the idea of keeping the Emperor, and it did have major implications in the way in which the Japanese saw the question of war guilt. If the Emperor wasn't guilty, how could any of them be? MacArthur and the throne ended up arguing that the war was committed by a small clique of militarists, of which Tojo was the most famous. But from the Japanese perspective, that meant that they had atoned. The Japanese nation wasn't guilty, a small clique of militarists was. And with the militarists gone, well, what was there to worry about?
Now, could Japan do more to atone for the sins of past, especially as its historiography of the war places a greater emphasis on the suffering they endured as opposed to the suffering they inflicted? Sure. But at the same time, it is also true that there isn't anything they can actually do which will cause China to stop waving the war as a nationalistic symbol.
One thing I find interesting is that I do find the talk about Japan very similar to the talk around the Confederacy. The American South never displayed the slightest in going for Round Two after Reconstruction, nor does Japan have the slightest interest in reviving the Empire again. And in both cases, you have people ignoring that real accomplishment in favor of arguing that the American authorities should have been harsher and broke the country it was occupying to fit more into 20th-century liberal ideals. And in both cases, those people miss the fact that ultimately, you can't actually wipe out existing power structures entirely.
It's not like the US had a mountain of fluent Japanese speakers who were just willing to go live in Japan for the next several years to serve as administrators. In fact, most of the people who had knowledge of Japan before the War were less willing to go as far as MacArthur and his cohorts did. These people were generally more exposed to Japanese upper-class society as opposed to the common people, and thus absorbed the Japanese upper class's argument that you couldn't democratize Japan at all because something something Asians are subservient peasants. By and large, the Americans who administrated Japan after the war didn't know shit about Japan.
This had some advantages in that they were willing to go farther. But the catch was that in order to actually implement anything, they relied a great deal on the pre-war bureaucracy. And while the bureaucracy itself was reformed to some degree, it did mean that turning Japan into a full-blown Western government would have been incredibly difficult at best. And that's before we get into economics: while the US was perfectly willing to funnel gobs of money to Western Europe to rebuild, they looked at Japan and declared, "tough shit. You get nothing." That is, until Korea.
