In AOE2 having the high ground is clear advantage. Same in SC2. In both games choke points matter.
But in AOE4 the high ground advantage has been removed. Only choke points is left. Granted some forests hide troops (SC2 has a similar vision blocking feature).
But is there anything else in the terrain that influences battles? I like the map design of AOE4 but it seems the tactical importance of terrain is quite limited?