A costly 60 muni upgrade in an army that is already muni intensive, should have a strong reward to go with that cost.
Sorry, this is not an argument anymore.
There is plenty of doctrines that allow resource conversion to muni, so you can have as much muni as you can dream about.
You already have 4 extremely different doctrines which can give you additional muni, either steady flow or huge burst of it.
That "muni heavy army" isn't muni starved anymore if you plan of using a lot of muni, you pick a doctrine that can supply you with it endlessly.
And its not like soviets are muni light. Pick any doctrine with guards and you have already a huge muni drain with a single guard squad alone. Pick T2 and muni suddenly drops down with light arty and precision strikes.
Just because a faction is not packed with extremely potent upgrades does not make it less muni heavy as soviets use at the very least 15 muni per single engagement, which quickly adds up.