If they made the world fully open then it would feel like a completely new experience.
EDIT: I don't mean they should make the "tunnels" on the map walk-able, I mean that they should think about how everything fits into place together. Put the puzzle together, work with the lore and figure out how people transcend flights of steps, how people walk the Limsa bridge etc.
Similarly like WoW map transitions.
EDIT2: For crossing the Limsa bridge it would be nice if they allowed mounts in city states too :). It would be a really nice touch to have mounts in cities.
