I see people got into discussing some about why spirits are as they are. I'll toss in my theories I've built up over the years.

1) Perpetuation.

I believe spirits were added around level cap 50. SE knew Freeze cost like 300 MP, so they attempt to use this as a guideline to set spirit perpetuation. It may also be pure chance that a spirit usually drained 300 MP post 50. And while 300 MP for a spirit freeze and 300 MP for a BLM freeze seems very fair and balanced, you have to keep in mind that you can also get 300 MP binds. This is something SE Developers apparently didn't think of.

If we on the other hand want to assume that perpetuation is not linked to spell costs, then we can assume SE simply choose an arbitrary value that was higher than avatars to A) prevent you from kiting things with spirits for long times and B) Make you more motivated to beat the high level avatars and use them instead.

2. Spirit Defense

While true it has 50% physical damage reduction, you also have to keep in mind they have the same def as a SMN. When you take 350 damage, the spirit will "only" take 175 damage. Spirits also have roughly 1k HP at 75. (And probably not much more at higher levels).

In addition even with 50 skill over cap, a spirit's interruption rate is terrible. Any damage over 30 has a large chance at interrupting the spell. Meaning spirits are TERRIBLE at trying to solo something to death through spells. Light spirit wins here with their 0.5 seconds Holy.

3) Ancient old cripple bug

Or rather what I call a bug, since it prevents you from playing. In reality all spirits have two modes. Defensive and Offensive. In Defensive Light spirit casts cures and buffs. In Defensive, all other spirits just hum around because SE didn't want to give them enspells or stoneskin or anything else useful. Well, they probably have them, just that they only cast spells on things they see, and they can't seem themselves.

The thing is, in defensive mode they have HALF spell timer, and in offensive full. So SE designed it so that on assault the spirit turns into offensive mode with full spell recast delay, and on release it goes into defensive mode with full spell recast delay.

Pros: We get self-attacking spirits guarding our weak Summoners.
Cons: It is counter productive to give spirits any commands, since it sets spell timers to max.

If you compare to puppets, they only have one timer system that never resets, but instead they do not auto-defend their masters. The question is... do you want to use your pet for damage, or for fleeing? Summoner has flee pet, Puppet masters have DD pets.


That is more or less my theories from over the years. SE made some clever code, that backfired. I'd gladly only have carbuncle as bodyguard and lose spirit bodyguards for working assault commands. Though I'd be even happier if they didn't cast random stupid spells as well.