All good points as to why Marines are the way they are. There are too many starting Cruisers/Battleships in the starting set up for Global 1940 2nd edition, which then greatly increases the value you get from purchasing enough Marines to fill your starting Cruisers/Battleships because it increases your overall “Amphibious Landing value” (total amount of units that can possibly be offloaded onto a territory in X amount of turns if all IPC’s are spent on transports/ground to go in the transports). Making Marines a 2/2/1 might be too strong in Global, but in the future sets I think you’ll need to make the Marine a 2/2/1.
So what I see happening is in future sets no one will purchase Marines after they have have enough to fill the starting Cruisers/Battleships. This is because the marine has very little value when you need to “shuck units” (usually involving 2 main groups of transports. One group picks up the units purchased turn before and lands them in your “shuck zone”, and one group that goes back to the purchase zone.), and you don’t want to build Cruisers/Battleships for your fleet because their cost/effectiveness ratio is horrible when compared to other sea units when you are looking at defensive/offensive value in sea battles. I would much rather purchase: infantry, artillery, transport, 2 subs, and a destroyer =34 IPC’s over 2 cruisers, 2 marines =34 IPC’s. So then you ask yourself what is the point of the Marine unit if all that are ever built are for the starting Cruisers/Battleships on the board? That is why I think for future sets Marines might be more playable at a stat line of 2/2/1 with text “+1 attack when Amphib Assaulting, does not receive bonus from artillery, 4 transport cost”. In future sets you might not have a lot of Cruisers/Battleships in the starting set up, and you can always balance the map appropriately to allow for the increased “implied threat” that Cruisers/Battleships give to the total “Amphibious Landing value” (total amount of units that can possibly be offloaded onto a territory in X amount of turns if all IPC’s are spent on transports/ground to go in the transports).