The T34/76 timing is really messed up. Comes way too late, especially if you build a M5/T70/SU-76 before. [...] Getting a T34 after PZIV as a result is somehow akward since PZIV beats it in AI/AT and armor.
The T-34/76's strength is not initial timing, but cost effectiveness. You can get the second one before or at the same time as Ostheer can get their second P4, you can throw one away and trade well against any vehicle bigger than a StuG. You can get about 3 for 2 P4s. After big tank engagements with multiple losses for both sides, it's the Soviets who can replace their armor the fastest. It's easier to achieve critical mass with it than with any other vehicle. And with ZiS guns as support, it does about as well at fighting infantry and tanks as a P4 for a much lower price.
That is what makes the T-34/76 unique, and it generally synergises really well with Soviets' attrition based late game strength. Messing around with the timings would likely cause a snowball effect (fast first tank leads to fast second tank, etc.) which would probably then lead to nerfs (like a higher unit cost) and turn it into just another medium tank.