I saw players climbing a fallen tree that was huge and then they had to speak to a tree creature that gave them a quest and then they performed magic from their butt and an animated skeleton somehow laughed, so ya, I think climbing trees will be possible there Vandraad. Got any other nit-picky musings ya want to toss my way or will you be content with your proverbial daily fart-in-an-elevator contributions to existence? ;-p
Yes, I now remember the Faerthale reveal where players climbed a tree! So at least SOME trees are climbable. Not to mention that at one point VR said (I'm paraphrasing) we aren't going to make some things climbable, we're going to make some things NOT climbable. Everything else will be.