If they add jump, lets keep it realistic like Aegis was pointing out. Have some manner of encumbrance value that will determine how high and how often you can jump. I don't know if they are keeping the ol stamina bar there but it could be quite handy for allowing you to jump but only a few times thus stopping the dreaded "bunny hopping" many are worried about in it's tracks.

Same could be done for swimming if they decide to implement it, hell I think they should let you drown if you tried to do something crazy like swim to Limsa. For example, if they added PVP content involving ships like they had in the demo video way back perhaps if you got knocked off the boat you could swim back over to it to climb back up. Logical uses for the mechanic that wouldn't ruffle any feathers really.