Now that I think about it, I don't actually see the problem with the whole BLM WHM thing.

Think about it. Conjurer has pretty much every single black mage spell already, right(haven't taken it up to 50 so I could be talking nonsense)? If Conjurer unlocks WHM at first(which we're not even sure that'll be the case), all that means is that those that want to heal strictly in a group switch to WHM and gain any and all abilities/bonuses conferred therein , whereas anyone who wants to nuke now has full leave to equip every single black magic spell they want and have at it as a straight up Conjurer. It's a win win scenario.

That's more of a temporary stopgap than anything though, assuming they stick with the 1-to-1 class/job unlocking for a long while at first, which I still don't like the sound of.