The yak 3 , lighter, faster and more acrobatic then the Yak 9 and with more rock n' roll and better pilots view. . .and they built a whole lot more of them.
So why the soviet hate HTC?
People still fly them all around the world (although they have better engines in them now) so I'm sure we could get a lot of data to put this plane into the game soon. . .
(prays)
There are loads of sources describing Yak-3 as more "nimble" than its predecessors wheater it was Yak-1 or Yak-7/9 series. Which is probably true considering the better power loading of the Yak-3 compared to the regular Yak-9/D/T. VK-107 engined Yak-9U (which we have in AH along with the Yak-9T) however was much different plane compared to the VK-105 engined 9s. Like I've said before, apart of the smaller inertia of the 3 compared to the 9U I really don't see how it could be "much more nimble" than 9U. The power loadings and wing loadings are very similar:
Yak-3:
Power: 1290hp
Weight: 2692kg
Wing area: 14,85 mē
Yak-9U:
Power: 1650hp
Weight: 3198kg (HTC)
Wing area: 17.2 mē
Power to weight:
Yak-3: 2,09 kg/hp
Yak-9U: 1,94 kg/hp
Wingloading:
Yak-3: 181 kg/mē
Yak-9U: 186 kg/mē
...and on top of that Yak-9U is faster on the deck and at the critical alt (which is of course higher for the Yak-9U than for the Yak-3) than the Yak-3.
As for the "soviet hate", they've added the very latest fighters into the Soviet planeset first, we have NS-37 armed IL-2 3M which was built in small numbers which slices through tanks like a hot knife through butter. The soviet plane set (almost deparately) needs beefing up but adding another somewhat redundant late war fighter doesn't really do much for it.
What soviet plane set needs right now IMO are Pe-2FT, LaGG-3, Yak-1b and a Yak-7.