This feedback has been in my head for a long time - engineers should be able to build this simple watchtower, a primitive elevation to see over their own defenses and better observe the terrain, in addition to sandbags, barbed wire, tank traps, machine gun nests, and normal base building.
I think this is easy to implement and would significantly increase the game feel, especially since the model already exists in REFORGER - you would just have to make it playable for the factions - maybe change it a bit so that it fits the factions.