I can't speak for the makers of this game, but I would venture a guess that being a US company run by (I would guess) American citizens, that of course there may be an affinity for the US stuff. Had this game been created in Germany or Japan, it might have been a slightly different story with a slightly greater emphasis on the aircraft of the home country. We generally grow up hearing stories mostly about the indigenous hardware. Yes, they would or do have to appease the masses, but who's to say the masses do not desire this or more US stuff? I am an American and I realize I fly almost exclusively the American-iron concentrating on F4U, P51B and P38. Though the war happened before my time, my family has lost family-members to both the Germans and Japanese and I would again guess that there is just an affinity for the US stuff when you live in the USA. Yes, I am generalizing and there are and will be exceptions. I look forward to Kates and Jills and early Zekes mostly because I want to fight them in Wildcats and Warhawks. If you want it your way, you kinda have to make it yourself.
Just one dog's opinion.
-Puke
332nd Flying Mongrels