9 minutes ago, Khobai said:but you can also get cover on the ground without having to climb. climbing is not necessary to get cover. so the advantage is theoretical because the only time it would ever be an advantage over cover on the ground is if there is no cover on the ground.
A lot off this comes down to the type of terrain used and the opponent you're facing.
For instance, in the picture below, my opponent was able to use the terrain to move a set of ARCS up (as seen on the left) to gain LoS on Dooku, who was still hiding in the back, catching him all but unprepared. Moves like this work well with mobile long range units like this. When my army went to return fire, because they were all on the ground, LoS cut through the terrain giving them heavy cover. It made trying to burn the ARCs on the left near impossible.
In situations where people are hiding units out of LoS (which is becoming more and more popular it seems) being able to gain elevation to see the unit at all (or more minis in a unit) can become infinitely more efficient than trying to achieve the same results on even ground.