Well the complaint by everyone is that the late game soviet mp economy is too efficient. Reducing xp gain on vet and new conscripts, thereby reducing field presence and increasing bleeding, and making reinforce costs 4mp more per model is a direct slight nerf to that overperforming mp economy.
Outside of vipper, who is that everyone you speak of?
The upgrade is designed to allow cons to win attrition battle and it does exactly that.
Don't bring exclusively small arms against them and they'll bleed just as any other squad, just not as cripplingly as they used to.
Other units inflict bleed by having better weapons and weapons upgrades.
Cons mitigate it by being durable and cheaper to reinforce.
Upgrade works exactly how its supposed to work by providing the above and a way to actually scale/be useful in late game.