I can totally understand the need for the developers to keep you out of certain areas of the game, and I know sometimes they do that by creating non-traverse-able terrain, but the one thing that really bugged me in oblivion was walking up a grassy slope and suddenly... the incline was too much and you were stuck. It was annoying/wrecked some of the immersion for me. I am all for slopes that are just way too steep to climb, but I think, for regular-semi difficult terrain you should be able to move across it with a penalty or you would need a climbing kit. How cool would it be to toss a grappling hook up a pile of rocks and climb it? Or, when you get to a wrecked fort you could scale the walls and sneak in the balcony door? It would definitely make thieving more fun. I understand Skyrim is not Thief, but it seems like it would be a relatively easy system to implement.