Why only 1 job per class?

[Carpe]

Okay... what determines which Class the Job shares its levels with if, say, both MRD and GLA need to be leveled to 30?

Will every Job have 2 class requirements? Will each have its own combination of classes, or can you, say, unlock BLM and WHM at once by leveling CNJ and THM?

I think the multiple class requirements are just to give a final fantasy tactics feel to unlocking jobs and to make sure that someone who has unlocked the job has a sufficient pool of abilities to choose from to perform that job. Like we see in the game now, your ability to tank increases greatly if you've aquired skills not just from Gladiator but also from Marauder and Pugilist. Having this additional requirement forces ppl to learn some of these skills so they'll be less gimp at doing what the job is intended to do.