Make resources valuable for Germany late war, they may want to cling to them as long as possible.
Granular VP diffusion makes fights for localized Cities a matter of 'prestige'.
Not just the BIG names of Cities.
The resources in Ukraine that they fought to hold on to, well, they had no way to get them back to Germany. I would think denying the Soviets the bonus for retaking cities early would cover that anyway.
Commenting a bit late here, and my WitE2 skill have become rusty for sure, so take my observations with a salt shaker full of salt...
To me it seems the GE player somehow missed the tempo in the middle, perhaps due to diverting panzers to north? Smolensk gates were reached on turn 5, but in December only 70-100 miles were gained past the city. Even though Land Bridge - Vyazma - Moscow is bad terrain, the GE player should (imo) force the SU defender to make desperate choices in that region, thus either creating openings for pockets, or steadily gaining ground.
On Soviet Reserves, 1M is quite a lot, but if the SU player is rotating rifle divisions, and preserving some units for future use the amount of men in the Reserve is going to be quite big. This is to some extent due to the forced 50% minimum MaxToE. One might have 20k-30k men in severely depleted AT units that are not receiving enough guns for quite a while, 50k-100k men in rotating/depleted artillery regiments etc. Disbanding units is an option to get those men on the field, but preserving experience and unit count is a reason to keep them in reserve.
I think in one of my AI games I opted to keep my Rifle Brigades in the reserve on 50% ToE so they wouldn't eat up manpower from the divisions. That brigade reserve alone amounted to 100k men in October '41. AI games are a different matter naturally, having the brigades on field could be a better option for HvH game, just to keep the counter density or CVs high enough in key areas.
Rotating rifle divisions may temporarily bump the reserves 100k-200k easily. Guards rifle divisions are best restored in the reserve, rather than in an active front area where supply might be scarce. Later on they can be deployed where needed for winter offensives, without using too much rail capacity.
