What good are these spells? Is there ever a reason to frenzy something that would attack you anyway? I can see where command would be useful, and charm works great, but what about these others that affect a creatures "outlook" towards you? Is there a reason to buy these spells? My thief specializes in Illusion as a major skill, mostly for invisibility and chameleon, but I need to beef up his Illusion rank as right now I don't have a high enough rank to get these spells. Right now I'm mostly just using charm on everyone I talk to.

Frenzy is sort of like, when you try to kill someone, they run for a gaurd. Frenzy them and they dont go for a gaurd but attack you instead.

So it's probably only good for assassins?

or when you wan´t somone to attack you but don´t want to get bounty, not sure if that works never tried it .

Frenzy is good for killing people you want dead but lack the skill to murder steathily so no guards see and arrest you.

Rally is for use on Allies, I think. Or it may make whoever you cast it on ally to you until the spell wears off or something. Not sure. Never used it.

Basically: Rally STOPS them from running away, Demoralize MAKES then run away.

Now these illusion spells are so confusing, but they are my favorites anyway.
I've used demoralize in Morrowind if I want to taunt someone into I a fight. I just need one taunt after using demoralize, and the person picks up the fight right away.