Player has experience on this game would know how to avoid checking LOS with eyeball on the house, forest or scattered tree since they are abstract with eyeball.
But, let's say if I have to check the LOS of an ambush AT gun using the LOS tool, I would switch to top-down view(6 or 7 view) that really make me feel I am playing CC. Making the game in 3D is not only for eye-candy I think and I hope CMBB developer would make even better use of there 3D game engine.
P.S. Some of the players say LOS tool is fine whenever camera or view suggestion get brought up. It might be fine for you all hardcore wargamers but I think there still alot of improvement could be done on UI and the camera view system.