The main Problem is, the game isn’t fun for every player, if you can only win as allies by almoust complete neglection of Japan. The Japanese Player will have a poor gaming experience. On the other hand, you won’t win the war in the pacific.
I recently invested loads of Russian troops, a UK factory in India and the US heavy into the pacific (1941 scenario) and didn’t come close to a win in the pacific and lost to europe. Eventough the Japanese player made a major mistake and i got lucky when he attackt some groundforces with mainly planes. The best I could achieve was a stall with Japan earning somewhat 50 IPC a turn (playing with NO).
While Germany on the other hand was playing extremely conservative, but finally crushed the USSR (rolling really good dice), so the US Invasion froce stationed in the atlantic.
Whats missing in this game?
I guess a industrial complex in India to start with could slow the japanese advance, while still saveing IPC for UK (doesn’t have to build one). This would make the game more challanging for the Japanese Player (otherwise there is no opponent on the continent) and gives the UK player more action on the pacific side of the board, while still able to build up some fleet to fight the Germans/Italians.