I do not understand why grenadiers (without a doctrine) scale so easily in this game while conscripts REQUIRE a doctrine to effectively scale.
Medic bunkers returned dead units into grenadiers rather than volks for a reason.
I understand what you mean and I've discussed about this with Peter from Relic. Basically Grenadiers are meant to scale slightly better than Conscripts due to the fact Germans lack elitè infantry like Guards and Shock Troops (PGs can cover one of the two roles being better than Russians only in the AT role and losing to Shock Troops in the AI role).
The thing is: the HP intel bulletins, together with the high output damage of the LMG42 make this unit vet very fast in the game standing the fight even when outnumbered, allowing you to have a couple of vet2-3 grens squads when your opponent has still vet1 conscripts.
This replay (it's still viewable) shows exactly what I'm talking about: even with hit the dirt and PPSh LMGs will get grens to vet3 so fast that your conscripts will either die before getting vet3 or will simply become useless.
After some experiments (as you can see in the replay) I think that in the late game M3s and flames are required to counter them. A late game Penal Battalion squad or flame engies into M3 could stand the fight, especially once vetted since they have more damage output than grenadiers.
The two issues that cause this "unbalance" are, in my opinion, intel bulletins and the veterancy system: the whole intel bulletins system is being looked at these days and should be fixed pretty soon, the veterancy system is something they are looking too but I can't tell you anything yet.
The only change I would like to see/test is a small indirect change to LMGs, like a slight increase in their cost or a small nerf on the accuracy.