Sturms are already in retarded possition. They are expensive, they need to rep, they need to sweep, they need to give heals (if you didnt go for Battlegroup) and also you want to give them flamenades and smoke garrisons?
I agree thet nades can be locked behind set-up, while fausts gehind trucks. But thats it. Also in regards to cover deniel, its not like OKW dont need this munition, constant spam of flame nades, may win you some engagements, but will delay STGs badly, its a trade off.
In a perfect scenario I would rather see flamenades locked behind mech track and smoke nades locked behind Battlegroup or vise versa. If anything volks need more utility rather then any other unit, because aside from snare, their usage in general falls pretty badly when upgraded\elite inf hits the field and they are non vetted (you lost vetted squad for excample).
The idea is that the flame nades are restricted earlier so that cheaper volks can't win cover fights against more expensive units. Late game when sturms need to repair and sweep volks will regain the capability. Early game when sturms are not needed they are the primary utility unit and volks are field control/holding units not semi elite assault units. Additionally the restricted flame nades would make stgs more accessible, but not compound into "I have my weapon upgrade so your only hope is using cover and focus fire but hahah if you stick I cover you will burn so better reduce that DPS while I mulch you"
Cover denial is extremely powerful, which is why the only other units that can do it are conscripts who have to pay for it and lack proper combat proficiency and stormtoopers/partisans whom both sit at 4 models and will melt if trying to prance up to an enemy position frontally and force them out.
But back to sturms and the OKW design philosophy. Volks are NOT supposed to be do it all units. Okw infantry game is supposed to be based around sturms early to get the initiative, then when trucks start rolling the game coasts a bit and relies on solidifying their gains, then obers and armour pull together the pressure late game. Volks are not supposed to be differently flavor led rifles thay carry the game from go to victory strike,×thats why there's not just 1 but 2 high impact infantry squads in the roster and more vehicles than any other faction.
The entire faction is supposed to be based on deciding how you need to use your limited high impact units (like sturms) and resources like fuel and munitions. over worked elites and picking and choosing what abilities and upgrades you need to prioritize is the idea, that's why you can get no pop trucks to pick up the slack for healing and repairs....