Would really like to have real alt support for end game.

[Galgarion]

That, and there's something kind of immersion-ruining about having one character who is The One and Only Black Mage AND The One AND Only White Mage AND The One and Only Azure Dragoon AND The Superest Duperest Paladin Who Ever Paladinned, etc.

Yeah, I used to worry about that for my little roleplaying sessions. Couldn't figure out a way for it to make sense; then I remembered it's a final fantasy game so the solution is the job crystals. You the Adventurer can be completely inept at magic but you can possess a job soul that isn't. You can even have different personalities for your character depending on the job crystal equipped. For instance, my Dark Knight crystal contains the soul of the great-grandson of the soul in my Paladin crystal. The Paladin can't believe any descendant of his would fall so low, so naturally they hate each other. It's a lot of fun, and a little meta, but it's completely logical and in keeping with established lore.