He's a repeatable lever that tilts the board every time he resolves
You are tacking on a slow ability onto a character with a stat line that is just asking to get Medusa'd and then not printing any really good targets for him
For Final Fantasy, however, the overwhelming demand has kept players purchasing product, even as prices soar
Crypt GhastCrypt Ghast, DeathgreeterDeathgreeter, ExsanguinateExsanguinate, Gray Merchant of AsphodelGray Merchant of Asphodel, and Vampiric LinkVampiric Link provide enough of a buffer to keep you jumping along (notably, Vampiric Link gains you life even if an opponent controls Kain)
Celes also opts to buff reanimated creatures instead of actually reanimating them herself
Granted, if you do the math you'll quickly realize that a creature Saga with three chapters can only attack once in a normal game of Magic