Japan already has a strong navy with 2 battleships and 3 carriers. it does not need more. What it needs are more land forces, which alpha provides: it adds 6 inf to China and Korea while removing 2 inf from japan
If your land units are at a premium and you have excess air units, would it not make sense to choose air over ground as casualties in select battles?
For example [OOB Global] when hitting Yunnan [3 inf] send in air and less land to keep the land units in tact. Choose these “excess” air units as casualties. Strike concentrated Chinese and UK land units with air to clear the board. Eventually, you’ll get your ground units there and the plane level would “balance” out.
This is not what I do in games_, but it does make sense in some cases and would not require changing things. I’d say maybe two-dozen games saw me select a plane in order to capture a key land area or keep a key land unit alive.[Like when trying to capture a capital.] Many times in Pacific40 I “taught” a new player not to concentrate Chinese units next to Yunnan without the UK air force, as I often flew in 16+ air to wipe away 10 or fewer units for 3-4 planes.[Especially if it nabbed the Chinese fighter.]_