Sure, just let me sink 240 fuel on fragile TDs, miraculously find enough tanks to kill to get both of them to vet 3 while not dying due to not having fuel for anything else! That's totally worth the investment for soviets to have the AT power of one JP IV!
End line, soviet t4 needs buffs.
Why not? Double SU-85 able to stop any heavy tank in the game except JT. In large team games there is plenty of targets for your SU-85 so it is possible to get at least one of them to vet 3.
They are not fragile if used defensively, on max range (just as intended).
And it is not like you need to roll out both at once. In my 4v4 games I usually build first one, then build 2 Katys, then build second one.
If OKW player have built JgPz.IV as first vehicle - he will not get any other vehicle any time soon. You don't need to deal with it right away, just invest more into infantry and indirect fire units so you won't have to fight it.
By the way, I'm talking from 4v4 perspective. I don't think that for 4v4 format Soviet T4 needs buffs.
But I should admit that I don't see SU-85 in 1v1s.