One of the first things that comes to mind when I think of Final Fantasy are the jobs, like White Mage, Black Mage, Monk, etc and that the characters were normally reined to one role and thus were indispensable for their unique abilities. (Well, for the most part that is.) It is this, I think that allows others to more readily respect and appreciate the significance of that specific role and player when it isn't so easily replaceable, or if at all. The player and their name sort of becomes renowned with that role.
I mean when if I wanted Black Magic I think of Vivi, the black mage. Martial combat? The monk, Tifa Lockhart of course. The list goes on, but if these characters were allowed to change their abilities freely, like lets say give Vivi a sword and Tifa a staff they wouldn't be as iconic to these roles as they are now.
Lastly I feel like allowing players to change their roles at will takes away from the traditional Final Fantasy experience, and overall makes it less gratifying to play a Job when you can potentially be replaced by anyone and everyone in your party at the flick of the wrist.
I feel as if the effort that comes along with making a new character for a new job that would make the Jobs feel more signifigant. The hard work only serves to bolster the sense of accomplishment once you've endured it. For example, the feeling of fulfillment for getting a weapon from a low-level dungeon is no where near as appealing than achieving a weapon from an end game dungeon. Like working hard to level a new job, there's a notoriety with earning a weapon from a hard boss.
In the end, I feel like it is this inherent "unappealing" nature of leveling and having to go through lots of work that would put a cog in the large proliferation of jobs and return that sense of accomplishment when you finally reached your level cap. Because personally, leveling in FXIV was so easy that capping out hardly phased me.
In the end, I understand why others like it and why it's detrimental to playing online, but just wanted to share why I don't particularly like it myself. Perhaps my ideals are a little dated.
Edit*
Again, I just wanted to clarify that I am not saying I want the game to change or I think it SHOULD be this way. It's just a personal opinion on something.
What do you think? (Sorry if this is a misplaced thread, or repeat.)