The Bf109E-4 was updated at the same time as all of the other Bf109s. This includes its exterior polygons. That it doesn't look good compared to the A6Ms or P-40s is simply an artifact of how long ago the Bf109s were updated. The Fw190s, Spitfires, P-51s, P-47s and P-38s also look very aged in comarison. The single stage Merlin Spitfire's noses are shaped wrong too.
Compare the Ki-84's cowling to the N1K2-J's cowling and you can see that the N1K2-J's has a lot more polygons. The Ki-84 may not be an octagon like the old A6Ms, but it is more angular than the newer radial engined models.
Now go compare the Bf109E-4 to, say, the B-26 or the C.205. The Bf109E-4 is clearly using more polygons.