The powerfulness of Shreck isn't the shreck itself or volks, just that OKW can spend all its ammo in it.
What make 1919 good but not that overpowered, the fact USF need ammo for many others abilities. Of course you can decide to invest all your ammo in it, but at the end, that's a strategic decision and it weaken you somewhere else.
Make volks shreck blob costing the same, but add or increase all other ammo prices of OKW abilites, add an ammo price to obers LMG, to falls, to jaigen to panzerfusiliers etc... and you' ll see a decrease of shreck spam. People will have to make strategic decisions again and decide how best invest ammo and fuel to have enough AI and AT on the field.
Today it is just easy to spend any single munitions point on shreck since you know you'll have ammo free AI stuff.
And that will work do you think? in fact this may cause the okw to be even more powerful. or do you think obers and fsj will remain 50 mp a piece? in the long term it will cause even faster vet for the obers and fsj with lower popcap and perhaps of facing 2-3 squads you are going to face 4-5 squads. Since the okw really doesnt have good ammo arty or abilities i tend to float ammo midgame.