there people go with that "easily" again. how do you know?
that implementation requires placing those walls around the world; rigging that animation; assuring the collision physics doesn't interfere with other models; assuring that skills used during that animation still work; rigging new animations for skills used during the wall running animation; determining how other mechanics affect wall running traversal; and probably a million other things that i know nothing about.
so what can anyone definitively say about the 'ease' of implementing a mechanic like wall running?
It's an easy solution for an otherwise big problem from a level-design perspective, as I have said. Of course it demands effort as everything else in the game, that's why they shouldn't have advertised it to begin with.