[dev1010] Spirits

[Alhanelem]

I would guess that the only reason they even exist is because avatars used to be difficult to acquire. SE probably felt that summoners should have something readily available other than Carbuncle back when Zilart first came out.

I must say though, that I've always found it odd that they have such a high perpetuation cost.

That's part of it- As I explained earlier- Summoner was added, sort of a suprise, with the prepratory patch for Rise of the Zilart. It does not itself require rise of the zilart, however all of the avatars do require an expansion, except for carbuncle which is given for free. If you didn't get the expansion, carbuncle would be your only spell if the spirits weren't there.