Plain and simple,
-- Population Cost lower = Lower Upkeep (Why is a goddamn 4-man gren takes up 7 pop cap)
Because grenadiers actually scale well into the lategame. Conscripts do not.
-- Reinforcement Cost: 15 manpower for team weapons?! I mean come on, I understand soviet has crappy inf and stuff; but 15 mp is way too cheap, not to mention there are 6-man = less risk to lose vet. Hell, even a gren take 28 to reinforce.
All weapon crews have a 25% mp discount compared to baseline infantry. Why should soviets pay a premium for their crews while the 3 other faction get a discount?
-- Maxim Rotation Speed: dont need to say much about this broken part of a machine gun. Are they ever gonna fix this?
Maxims are the only thing that the soviets have that has both legs and that is worth getting. Without OP maxims the soviet combined arms army is a bad joke.
-- ZiS artillery shots: In reality, every AT guns in the war can fire HE rounds, why do soviet get this privilege?
Because the ZIS3 gun has bad AT-capabilities. A PAK40 has a significantly higher rate of fire and better penetration. Asymmetrical balance. Why do germans get the privalige to upgrade their baseline infantry with heavy weapons while soviets can't? Asymmetrical balance.
-- Maxim ZiS spam: Easily see this in 2v2 games, maxim rotates fast enough to act like a normal inf squad. While 3 ZiS can even hold off the heaviest armor from Ostheer, it makes SU85 unnecessary.
Maxim/zis spam is extremely vulnerable to artillery. L2adapt. Hit the field guns with artillery and roll in with your tanks to finish them of and force off the maxims.
I agree that the soviets can be boring to play and to play against. This is because soviet combined arms isn't that great and they rely heavily on doctrinal cheesy stuff to make up for their lack of good stock units.
I play a lot of 1v1 as soviets, and I can tell you that the only way you are going to stand up to the germans with soviets is when you abuse the shit out of some units and a very small set of doctrines. If you try something more fun like a combined arms army with irregulars and a howitzer you will just get stomped by unkillable tigers in the late game.