its levelling system may be one of the best ever implemented in any Final Fantasy title
No...just no. The leveling system was basically the sphere grid from ten....with zero choice.
The biggest problem most people had with this game was that there was no exploration, no choice in where you go, just an endless corridor from which there was no escape. This extends to the leveling system which is basically a straight line. Why even bother with all that flowery nonsense disguising the fact that characters have no choice when it comes to leveling, why not just give them a point for however many XPs and have them spend it in that class and just gain the relevant upgrades and skills, and then there was the artificial limits, restricting your ability to advance until a certain line had been crossed in the narrative. Basically you fight when told, you advance when told. This really should have been a visual novel, might have made the whole thing just tolerable to me.