There never was a "G10" to trade. It was always K-4 performance with totally unhistorical weapons options (things a K4 never carried, ever).
On top of that, G10s came out after K4s, and had worse performance. They fill no gap, they do nothing for the planeset.
The ONLY reason they were there was the same reason the G-6 had 30mm and 20mm options: to give variety.
It leads to frankenstein flight models. Like the old Spit9 with round US-style drop tanks, 50cals, but early 1942 engines and later pointed tail... It makes no sense to have frankenstein models. Thankfully HTC is moving more toward accurate (historical) models as they revisit these old planes.
Forget the G10. Folks never flew one. Folks never got attached to one. The plane they flew and came to love was a K-4. Always was, always will be, the only difference is NOW it has only the weapons it flew with in WW2.
You wouldn't condone a P-51D with 4x20mm, would you? Why would you condone a K-4 with WGr21s, 20mm hub, and 20mm gondolas?