The T34 has been popular several times in the past, just not in insane modes like 3v3 and 4v4. The original ROF would give it a good increase in DPS and a small price drop would go well with....
Damn you NDA! *shakes fist!*
2 times.
1) At the start of the game, where both IS-2 and T34/85 was a waste of resources.
2) When industry was at its prime.
And thats pretty much it.
Every single other time you've seen it was "because its stupid to go for same late game tier as dual sov" or someone did T-70 rush so he was forced for 34/76.