I think it would be cool to have the climb skill added, since we already have the animations for climbing ladders. Climbing stuff was always a staple of my pnp games, I mean who didn't buy 50' of rope and a grappling hook? This would give rogue types more usefulness too, if you had dungeons where there were levers or runes up on ledges that needed a high dc skill check to climb too. It could add a new tactical aspect to battles, if you could climb up to a ledge and rain down arrows or spells.