I wouldn't really consider 4 of a basic, non-weapon team squad to be spam.
Anyway, I feel that you are not really accounting for the fact that most of the things you describe are intentional. Grenadiers w/ LMGs are intended to be able to shred Cons at medium long-range - without this, Grens would be near-useless and not worth building at all. Just think about how much of a nerf to Ostheer your suggestions would be. Is it really true that LMG DPS is breaking the game? It was tuned down about 3 weeks ago in a major patch, and I would argue that reducing this any more would severely damage faction balance. As it stands, LMG Grens are strong 1v1 against other infantry squads at medium-long range, but there are many counters and many other situations in which they do not perform as effectively. Same goes for Rifles.
You also need to consider the fact that 4 x LMG upgrade = a huge 240 munitions. This represents a very significant trade-off against grenades, mines, Panzerschrecks, arty and a lot of other things.
breaking the game? no, but there's too much of an unfair advantage over rifles and smg infantry. lmg is still, the mother of all infantry weapons, the king of A move tactics and needs some toning down.
what i ask for is a toning down to manageable levels, not at its current levels where lmgs provide such a huge upgrade to a point where they match elite infantry. most elite infantry are also more expensive than grenadiers by a relatively huge margin, about 90mp/75munitions more for guards, 150mp more for shocks. that 60muni investment actually more cost effective than elite infantry. for 240mp and 60munitions to match elites, it is relatively cheap. so cost wise, there isnt really much to compare, the lmg upgrade is just so much more effective.
a common scenario of 2 cons + 2 guards (1140mp/150munitions) vs 4 upgraded grens (960mp/240munitions). in a straight up fight, the grens will mow down everything in sight before taking any serious casualties. if grens were to a move towards 2 cons and 2 guards, rifle nades will make short work of guards who have to stand still to fire and should the guards leave cover to throw a nade, they will be shot to bits.
another scenario of 2 cons + 2 shocks(1260mp) vs 4 upgraded grens (960mp/240munitions). this could be even more one sided as long as grens maintain long range, nothing can scratch them. however, should shocks get close, focus fire and soft retreating the gren squad in danger should force a retreat. so for soviet infantry here to do real damage, it is very situational and extremely risky.
design should never interfere with balance or overperformance. as long as grens has an advantage over cons, it meets the design. grens match cons without lmg and if you mean cons are currently useless, you should then know that grens have too much an unfair advantage over cons.
with lmgs, cons, penals are invalidated (read free exp), guards struggle and shocks become situational. in order to match 4x grens and prevent them from rolling over infantry, you need to lock them down with enough dps or pin them down. considering they have access to rifle nades and that huge ranged dps, maxims will have trouble suppressing them before the gunner gets killed.
also, this problem was faced when browning lmgs were spammed. grenadiers, volks, fusiliers, obers or falls had issues standing in the sheer firepower of lmgs and the amount of crying was immense.
what im saying is, the long range lmg nerf is not good enough, more has to be done.
about faction balance, okw far outperforms ost and ost is still at a very good spot. since wfa, sov and US received mainly nerfs, so i dont see a balance problem. usf still have no counter to sniper, sov have no hard counters to gren spam except by taking a huge mp bleed mid to late game. the reason for okw popularity is not because ost suck, okw is just far better.
insta pin mg34? check
almost insta pin mg34 on wheels? check
non doctrinal heavy tank? check
base infantry with good scaling? check
counter to isu152? check
cheaper teching progression? check
noob friendly? check