That was actually what i was proposing... t4 independent of t3... t4 to 120 fuel... it would make T3 into t4 more expensive... but make a t4 rush strategy stronger...
They are not going to do this due to how the faction is designed, they stated many times that they want the tanks in T3 to be used more often and give them an actual purpose.
I know it's bullshit, but it's as simple as that, it's the only reason you can't skip T3, other than needing a T70/SU76 depending on the situation.
It's also the reason T34 went to T4 even though it's not a very strong tank.
It's not that hard to figure out, both T3 and T4 are expensive.
The M5 car is not used often not because it's a bad unit but because it has no use in the current meta, this unit needs absolutely no changing.
If you made T3 faster to built, players would consider adding the M5 in their build order.
The same goes for SU76, althought this tank still has good use, you don't see it much often because it's a whole lot better to rush T34 asap.
T3 and T4 should cost 250/70 instead of 240/80 and 240/90.
I don't even see how it's up to debate, the thing is so obvious, it's as obvious as when OKW got medics, snares and grenades out of one teching, relentless discussion went on that until they finally changed it.
Soviet design is inherently bad, because the meta in the game has become too stall.