If you knew SE, you would know that a direct progression from a base class to an advanced class was started in the first Final Fantasy. A black mage would become a Wizard. And thus have a different tree of talents(spells) to use.
Has WoW really become so large that people think that Final Fantasy is stealing from WoW and not vice-versa? Next thing you will be telling me that the new Zelda game stole it's main villain from an NPC in Oggrimar. or that Napoleon Dynamite was a total-ripoff of the Blood elves.... or that Lord of the Rings stole that wicked helm from the Lich King for Sauramon.
FFS, WoW steals EVERYTHING, and it made the game great. Let FF follow that path please.