I sort of wish players could only choose one job.

[Duelle]

VI (all characters can learn all magic, so any character can be the main heal/buff/nuke. stats are also manipulable)

I wouldn't call that "customization" when magic was pretty much the only thing that could be shared between the characters. Each one was built as their respective classes and then magic was sprinkled on top. Most of the personalities were even reflected by their chosen classes.

That being said, most of the games to date have a great degree of role swapping, if not job swapping. Remember that I decided not to include the Tactics games, X-2, XIII-2, Dimensions, and even an off-shoot like FFCC: My Life as a King, all of which allow a great degree of freedom over jobs.

Not so much role swapping. What they did is give the player a bunch of characters that were not defined by anything outside of what you did to develop them. The resulting game mechanic is great because it also plays into the fact that unlike MMORPGs, you don't need the trinity in a console RPG. You have have a heavy armor character with strong melee attacks and strong heals and no one would cry "OP" and demanding nerfs.