And you know that player freedom has been sacrificed because... oh right, you don't know that. But yes, it's totally because of them spending time making your character look cool in 3rd person.
I don't know for certain, but it seems fairly obvious to me from everything i've seen of the game thus far that we're going to have to rely on set paths to get up most mountains.
And I really don't think you've ever done rock climbing, much less tried assaulting a mountain summit. There's a reason that everyone climbing Everest has to go the same way. And again, no one seems to feel that the world is conspiring to limit their freedom.
I've done plenty of mountain climbing in Scotland and Wales, and I can tell you now, there are no set paths everyone has to follow - you can climb most mountains from any direction you like and make your own route. Obviously some ways are going to be harder than others, but it's completely your choice which way you get up to the top. A thousand people could all climb the same mountain at one time with no two people taking the exact same route.