Is it possible to add terrain deformation, I don't know but it would open many possibilities to tactics
Entrenchment tools could be add like in A2
Engineers could carry them by default and would have the ability to dig twice as fast as others
A series of holes can be dug to create trenches
Create your own H-barriers
The ability to cover up planted explosives
Blow your own foxhole with some C4 if you don't have an entrenchment tool
Make a trench on a well travelled road to slow vehicles and ambush them
I know the game has limitations and going below ground level is an iffy subject
but only a meter or so would be nice
The ability to climb would help tho even if its only up to anything that is chest height