I agree, it was pretty dumb in my opinion to try and cram all of the games magic into 2 classes.
I'd be fine with it if those two jobs were White Mage and Black Mage -- that's a distinction that goes back beyond even the first FF game. In a game where you can use abilities from another job any time you want, there's really no reason to have hybrid jobs.
But, two mage jobs that are both
a mix of the two magic types makes very little sense.