Just because it's been asked for for years doesn't mean it really needs to be in the game. B-29 has been asked for more than the Brewster, but doesn't mean it deserves to be in the game any more than, oh P-39 or Me410. (for example)
Brewster had smaller wing area than the F4F-4, much less power in the engine, less firepower. Less power + smaller wing area = less turn capability compared to the F4F-4. It was very slow, and unless you model the version with armor (weighing it down more) it would light up faster than an a6m2.
I really think that the only reason the Finns want it is national pride, and hell I can sympathize, but they make it out to be some super plane where it wasn't, IMO. The performance was all based on the Finn fighters, not the aircraft used.
The Ki-43 would definitely be a good addition. As long as it was modeled properly. The early models had 2x 7mm MGs and a top speed (at alt) of 309mph. Heck a spitV does this at sea level. Anyway, they produced a clipped wing version the IIb with some armor after a few nasty run-ins with allied fighters. The IIbs had 2x 12.7mm MGs with 250 rounds each, but a top speed of only 320mph at alt. Very few examples of the IIIb were made, and it wouldn't be very accurate to include the IIIb if you're looking for a mid-war gap-filling aircraft.
I'd hit it. But then,
I can get kills with 2x 50cals, I know a lot of other folks can't
The main problem would be flying 100+ mph slower than every other plane around you