i think the numbering of spells stopped for a while since Final Fantasy VII (referring to mainstream titles), and then it picks back up with an epic record in Final Fantasy XI. i suppose it's logical in Final Fantasy XI's sense, otherwise a WHM wouldn't have the need to go so far if it was just Cure, Cura, and Curaga. Final Fantasy XI is actually a mix between numbering them and adding suffixes to a crazy point.

now, for my opinion - the names can be somewhat longer, but i fancy them more. they'd work better with Roman Numerals (instead of Fire3/et-cetera), at least while it doesn't get insane...