>>723248764
It's a consequence of the Onion Knight being the default Freelancer job since FF3 was the test-bed for the job system in general, there isn't really any material for Onion Knight's EX mode beyond job changing because it was FF3 (hence also the Ninja + Sage combo, FF3's endgame melee and caster), and it's more readily recognizable for him to be an Onion Knight than it is for his Amano appearance to be used

He became a character unto himself as a vague representation of FF3's four generic adventurers in a similar manner to FF1 gaining Warrior of Light based entirely on Amano's artwork and WoL becoming a fixture of party leader for three generic job holders in FF1 adaptations like Stranger of Paradise, but Amano's art for FF3's protagonist(s) did become a costume