You raise good points. However, the 3 transports could be sent back to Japan and used in the Money Islands. If Japan built a factory in FIC and perhaps even another in Shanghai or HK, it could theoretically have enough naval cover for transports to hit the Money Islands and enough tanks to check India and China. All of this, though, would make that Australia Capture much trickier… Perhaps Japan should use that FIC factory to go for Calcutta instead?
So let’s game it out a few rounds:
J1 buy 3 transports
J2 take Hawaii and Money Islands
UKPac/ANZAC 2 they retake 2 islands
J3 3 transports return to Japan
J4 3 transports reach Philippines
J5 3 transports reach Money Islands
So, if ANZAC/UKPac sink your original 3 transports after J2 you won’t have the Money Islands for 2 full turns. That’s a 32 ipc swing - you may not lose all of the islands, but income also goes to ANZAC/UKPac (so, -13 for you, +8 for them each turn for sure). You also won’t get Malaya on J3, which is another 22 ipc swing against you. You lose 6 ipcs that UKPac keeps and ANZAC gets 10 ipc NO bonus.
Also, no mIC and no spare transports means no extra troops on the mainland until at least J3. If UKPac is good, you won’t be able to build in FiC because he’ll be threatening to take it and you won’t have transports to reinforce it unless you buy 2-3 more on J2 so you can land on J3.
Now, maybe ANZAC and UKPac use their transports on turn 1 and instead of losing the Money Islands between J2 and J3, its after J3. That’s good, and they’ll have to replace them but still a lot of lost income.
Best case scenario I can see, if your opponent is good but not a wizard or anything is:
US loses 14-21 ipcs, 2 inf, and 2 fighters (maybe)
UKPac goes +14 ipcs (or more)
ANZAC is +18 ipcs
China +12-18 ipcs (you won’t be able to keep Burma Road closed)
Japan will: lose 3 transports, no mainland factories building until J4, about -40 ipcs (approx)