I guess the issue is that with Nazi Germany you have quite detailed plans of what they wanted to happen after their victory and a legitimate argument that their foreign policy from 1933 onwards was directed towards those goals. You could make a similar case for Italy (although I doubt there's much will to organise a Mare Nostrum Victorious) but with Japan it just isn't there. The Pacific War fascinates western audiences almost as much as events in Europe but there isn't nearly as much willingness to understand the roots of Japanese aggression. The fact that it requires a worldview with East Asia, and more specifically China, as its nucleus is intimidating to many western writers let alone audiences. Couple that with the fact that a lot of policy was determined by the Kwatung Army or IJA doing something and leaders in Tokyo signing off on it retroactively out of fear of assassination, with any rationalisation coming afterwards, you can see why there's an eagerness to just have Tojo as Hitler and the supposed Tanaka Memorial as Mein Kampf.I feel that while Imperial Japan is less focused on than Nazi Germany, I feel the biggest elephant in the room is that the Second Sino-Japanese War, which indeed was the very lynchpin of lead up to the Pacific War, and what Japanese objectives are still ignored. The general assumption still seems to be the Japanese actions in the Pacific are basically to facilitate out and out conquest, when all their actions not in China were done to either cut off Chinese supplies, or once war became inevitable secure fuel to continue their war in China. And even with the Second Sino-Japanese War itself there is no real telling what Japanese war aims could have been, since it was caused by an escalation similar to the Mukden Incident.
Didn't ruth from AH.com make a timeline complete with wikiboxes from this scenario?Another factor is that Imperial Japan just wasn't that weird. Nazi Germany was a state with an insane vision for the world, Japan (at least in the popular western imagination) was just a bog standard "you have stuff we want, so we'll take it" dictatorship. Plus, well, China ended up as a US-hostile (at least for the early cold war) dictatorship anyway, so there's less interest in exploring the Japanese victory scenario.
Still, might be interesting to have a Ye Olde Axis Victory scenario where Germany falls over from partisan activity, no more economies to loot, and generally being insane and Japan becomes the dominant power of the world.