Besides masking loading, I think these are put in to break the pace in games. If all you’re doing is going from one fight to the next, your mind is a bit too locked in. Climbing is less effort on your mind, without making you pay attention to story.

I also found in games like Expedition 33, they help make the world feel more alive if you’re clambering through low caverns and climbing up cliffs. The way the verticality lends to better vistas is itself pretty valuable.