That is simply not correct. Volks are only 'weak' until T1 or T2 is built. Then they have their StG44 and Fire Nades which will make them win every engagement from mid to close while being in green cover.
Volks (and Grens) are not a rushing unit, if you try to storm an enemy position, they will lose. This is intended.
If you play against OKW, you will see that Volks are a pain in the ass because they get incredibly strong the longer the game goes. In the first minutes, Vet0 Volks are a piece of cake. But fighting against Vet5 Stg44 Volks is something that can be really frustrating.
Also as Allies, Sturmpioneers are cancer, honestly. You have to make a 'lucky shot' and let them drop at least 1 (better 2) model(s) when they are closing in in the early game, otherwise you have to immediately retreat in order to prevent a squad wipe.
Volks (in live) already lose in an even fight, saying they they win in green cover is awful...IT CLEARLY implies that they should lose even with better cover.
Their flame nade is having a timer, their veterancy nerfed (which could be ok, if it wasn't that their late game performance vs cost, already bad before, is terrible now and make them UP..which is the reason why i simply proposed to roll back any change abd remove stg for a cost reduction).
Sturmpioneers are perfectly fine..it's a 300 mp unit that already fill your popcap and reduce income.
Okw starts with less mp because of that starting unit that combat wise is terribly situational.
It also bleed terribly and requires micro and placement skills to have some effect