I don't remember what post it was from by Yoshi-P, but I was under the impression that we'd only be able to jump at certain points, like on FFXIII. Honestly I think that would suit this MMO a lot more than watching tons of players jumping in place or hopping like a kangaroo across the plains.

Edit: hit the post button too soon lol ... I think chocobo jumping would be awesome if it was done like that anyway, even if the player jump system isn't.