I wouldn't design Red Mage at all, especially at this point in time in the game.

XIV needs a more dynamic mage class than a "combination" class/job. It also doesn't need a melee mage class right now either.

The only reason people want Red Mage right now is for refresh. Having an entire class made and implemented just for Refresh is pretty sad.

There are plenty of opportunities for SE to create a more inventive class/job than Red Mage.