Yes, I see that point, but I think their overall performance is very good. So in my opinion reducing the MP cost can only work if they get nerfed for late game. But then you could basically buy just Volks.
And as I said, of all the factions, OKW can take the early game blow due to their Sturmpioniere.
Also I thought that vetted+upgraded (I know, 30 mun difference) Panzerfusiliere are better than Volksgrenadiere? This was basically the whole point of the redesign, wasn't it?
Actually OKW is the faction that can NOT tolerate early losses because of their mid game weaknesses. Yes the sturmpioneer is strong but by any mistakes early with sturmpioneer you are screwed. (Sidenote : Maxim spam completely shut down OKW)