Whenever the subject of Blue Mage comes up, this is the main obstacle to adding it into the current battle system. Even Yoshi-P addressed this before last year when the subject came up.

Now, the thing is: none of the other Disciplines of Magic had to purchase their spells from a magic shop. They either learn it via level up, just like Final Fantasy IV and the Dragon Quest series, or through a class quest.

If BLU were to be added to FFXIV, why should it be any different? Is Blue Magic defined as learning abilities from monsters, or using otherwise exclusive enemy skills?

There's also the subject of party role: how it could fit in the trinity Looking at Blue Magic in V through X, it was always an eclectic school of magic that nevertheless mostly focused on dealing damage. In that respect, I'd say Blue Mage would be best implemented as a Ranged DPS caster.