A possible explanation for the Pacific Theatre's (relative) lack of commercial appeal: the Japanese lacked cool armour.
The great variety of German tanks, self-propelled guns, half-tracks, etc. really "makes" the hobby for me. As vicious and vile as the Huns were, they produced excellent AFV - and these translate into exceptionally intriguing toys. Panthers, Marders, Tigers, King Tigers, Mark IVs, Mark IIIs, Jagdpanthers, Jagdtigers, Hetzers, Flakpanzers ... take your pick.
And what did Japan offer? Not much - crap tankettes and mountain howitzers that made Poland's armored corps look like world-beaters. When a modern company begins to develop product plans, based closely on historical events, they're really basically restricted to a whole bunch of mad dog Jap infantry squirreled away in caves and bunkers.
And I don't think that's all that sexy, from the standpoint of appeal. Sure, we all appreciated the occasional Marx, Airfix and Britain's banzai foot soldier attack across the sandbox as kids, but these were generally turned away quickly and with great slaughter to the attackers.
They needed tanks back then and they need them now - and that just ain't going to happen.