Your approach basically assumes that they make arbitrary nerfs or buffs in the first place as if they were in a vacuum. Everything has to be done relative to other units, you don't make something more powerful just for the sake of making it more powerful.
You could, however, argue that the changes to, for example, the 222, were too significant or not warranted at all, but you would need evidence for that, which I assume relic had in order to convince them the changes were needed in the first place. (I'm not saying that I always agree with relic or anything) I don't think anyone would argue that the 222 wasn't underperforming before the changes. Maybe they went a bit overboard and it could use some further adjustment, I'm not sure.
The entire idea of "balancing" is based on making slight changes to that very delicate ratio of cost/performance until the unit fits well relative to other units. There's a reason skilled players will consider spamming maxims but not mg42s.
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.