if jobs were substantially different, like most of us wish they were, then i say they are stupid to not do it that way. Becuase its more of a "tack on" pretty much there to say "hey look guys, something FF!" and is more of a minor change from what we have to specifiy roles, i would rather not, honestly they way it sounds, its like playing the same class for 50 levels again with some slight skill changes.

either way, if they did it with a new exp bar, it would have to be set up completely new. new weapons, armor, skills through cap...ect. The system they have is equip stone > quest a hanful of skills/gear...done