You have people that complain about blobbing and then they post complaining about infantry that can build cover and effectively use it...
I'm sorry but if bags gets removed or "timed" all you'll see is massed blobs roaming the map slamming into each other. Moving it to engies is not the answer because as it stands USF hardly use tank traps for green cover compared to other factions.
The only winners of this change will be blobbing USF players that have their infantry balanced around the fact they don't need cover like Tommy, cons, ostruppen or even volks do.
How do you really back up your argument? I mean i can say anything unrelated and even picture a doom and what i just did was not even an aswer. There are always bad cases and the worst players often exploit it but by no means those players decide what balance actually is.
Sandbags being limited will force a more strategical perspective on the game. If you like to blob like a maniac someone waiting calmly in green cover should rape the crap out of that blob. This change brings another step into a more skill rewarding gameplay. Blobs will always exist and mostly on low skill players or on unbalanced cheese infantry.
I will repeat my suggestion, mainlines should not build GREEN cover but dig shallow trenches, that provide light cover. It shouldnt be too hard to code, its just a feature to the map, like a crater but with directional cover. A trench can be or can not be destroyed when trampled (it should be though) and infantry can past on top of it without vaulting. This gives green conver more value