I'm not sure why, but it seems like there aren't very many in the community who are interested in the PTO. See my poll about Japanese fighters in the Aircraft forum-- if we get a lot of votes, maybe HTC will give us some more Japanese planes!
Not to take anything away from the Luftwaffe, but there is a lot of variety to be had in the PTO - combatants included the USN, USAAF, British, Dutch, RAAF, RNZAF, and the IJN and IJAAF. Where the Germans concentrated on refining the basic design of two airframes (Me109 and FW190) for the most part, the Japanese produced a number of different designs that included lightweight dogfighters to fast-climbing, powerfully-armed interceptors.
Maybe the lack of interest has to do with the Japanese air arm's relatively poor showing in combat from mid-war to the end? But I think this poor showing was primarily due to training deficiencies and other factors that would not be represented in AH - so in the MA, the late-war Japanese designs should give a very good account of themselves (notice how well the N1K2 does).
I'm still hopeful for more Japanese planes beyond the Ki.67, which is certainly a welcome addition to the Japanese hangar.
Please keep up your lobbying, banana!