WHY???? we have like 10 variants of each!
Think of it this way. German vs. US.
How many US fighters are represented? P-38, P-40, P-47, P-51, F4F, F6F, F4U. Seven different airframes; multiple variants for each except the F6F.
The Germans? 109 and 190. (I'm excluding the 163 and 262).
That's reason number one why we have "so many" 109 and 190 variants. There were only two airframes used.
Reason number two is that those two planes were continuously upgraded - and significantly so.
The difference between a 109E-3 and a 109K-4 is huge; as is that between the 190A5 and the Ta-152. Each, respectively, might as well be from a different planet.
By contrast? Consider the slight differences between the P-51B and P-51D.
That's my opinion, anyway. Besides; who would argue against more airplanes, regardless of type?