IMO, K4 is fine, it's the only German fighter that can catch and outfly most Allied planes (190D cannot out fly but they'll BnZ you to death). You don't see hordes of K4s and Doras, but you see a crap ton of P51s and Spit16s. I don't see AH as a 100% historical sim, because if it was, well, it wouldn't be a very fun game.
I see the K4 as a balancing factor, each country gets their own LW monster that can compete in the MA.
109K4, 190D, Me-262
Spit16, P51D, P47M, Tempest
La-7, Yak-9U (to a lesser extent)
The Japs and the Italians should be the ones that are against this wish.
Add the G.55 for the Italians (hey, we have the Ta-152, G.55 meets the criteria). And for the Japanese, I'm not sure what their LW monster ride is.