First of all, Japan trying to take Los Angeles would be foolish unrealistic and not a world war 2 game, but something entirely different.
Secondly, the answer to the US ignoring Japan, is not force the US to almost ignore what is, was, and should be the greatest threat which is Germany. This is still a world war 2 game, not risk with a map of the world.
Thirdly, the game as it is today, in my opinion, if Japan was totally ignored, could end up easily taking Anzac. So if you raised the VC limit to 7, then taking Hawaii and Anzac would produce a victory.
But the answer, the true, historic, realistic, keeping it simple answer to the lack of action in the Pacific problem is now obvious. You can’t ignore Japan, you just can’t, but the majority of resources still must be spent of Germany to keep it balances. So how do you encourage meaningful action in the Pacific without altering the balance of the game in an unrealistic, and unhistorical fashion.
BY DRAMTICALLY LOWERING THE RESOURCES IT TAKES TO BUILD A NAVY SO REAL BATTLES CAN BE FOUGHT WITHOUT SACRIFICING SO MUCH IN OTHER MORE IMPORTANT FRONTS.
Navy’s are way to expensive. Make them comparable in cost to land units.
Transports $3
Subs $4
Destroyers $5
Cruisers $6
Battleships $9
Air Craft Carriers $6
Planes $8 and let them pick there targets at sea. Each side would then have planes and you would get realistic air to air battles.
This is keeping it simple to the core. Germany would be able to fight a real Atlantic battle and would offset the cheaper transports for the US.
Japan and the US could go at it without sacrificing their other theatres. Japan could really threaten Anzac and the US could build a real Navy without sacrificing so much in the European theatre.
This is the answer with the new setup.