Originally Posted by
Metathetical
This would be a great way to add hotbar bloat without adding much depth, because 90-95% of the time the enemy wouldn't resist or be weak to any elements so you'd just pick whichever element you like the most and go through your rotation. And for the other 5-10%, you'd just... do the same rotation but with the right element. The only times where it might possibly be interesting would be if you had mixed elemental resistances in the same pack.
Think about the other single-player FF games: elemental weaknesses basically never forced interesting choices, it just became 'equip this weapon to deal double the damage' or 'only use fire magic'. That's boring.