That's a moot point given the asymmetrical design of each faction. Even if say, a unit is rather crap to start with (looking at the T34/76 >.>), making it cheaper won't mean it's suddenly more viable. People are more likely/happier to pay a higher cost for a unit that performs as it should (or inversely, a unit that overperforms for its cost).
I'm not saying that the 222 is "OP" or anything like that, as it's good that it has finally found viability. But for its cost, saying that it's too cost-effcient for its utility is a valid argument to make. Especially using your own argument in this case here.
Spammed MG42s can be countered, just as spammed Maxims can be. Hell, they don't even have to be "relative". As long as their intended counters cost and work as they should it's alright. That's the idea of asymmetry.
The T34/76 in itself isn't crap. It's only crap relative to other units of its type (medium tanks) that come out at about the same time. Also, making it cheaper would definitely make it more viable, but that is not the appropriate balance change to make in this case. If they only costed say 50 fuel and 250 manpower, it would be a great unit.(obviously I'm not suggesting this) People would spam it because you'd get such good value out of it. It used to be in kind of a nice place, being a low cost medium tank that didn't require much teching that could come out before its competitors (maybe a bit too much before) such as the P4 and then dominate the battlefield for a short time. They completely killed it once it was moved to T4, you never see them anymore.
Just because the factions are asymmetrical doesn't mean that you don't have to balance them in relation to each other. Ideally you get the same value out of two different units that each cost 280mp each despite them have different strengths and weaknesses, that's the challenge of balancing a game like this.