OK, this was a rant, not a logical dissection of things, so I may have gotten a bit clouded and murky there. Sorry.
I'd like to say that unbalanced means they are unbalanced - not that they are not useful. Divination is supposed to be weak, but I assure you in my campaigns it isn't. Ubalanced is unbalanced by the rules, it does not mean that a good player or DM can't squeeze great uses out of it. But it does mean they'll have to jump through hoops to do so regularly.
So with that in mind, let me try to demonstrate the imbalance in the rules.
Enchantment
Enchantment spells affect the minds of others, influencing or controlling their behavior.
All enchantments are mind-affecting spells. Two types of enchantment spells grant you influence over a subject creature.
Charm: ...
Compulsion: ...
A simple 1st level spell protects you completely from all [summon], [charm], and [compulsion] spells. No need for 8th level spells here. The most prominent enchantment and conjuration spells are negated by protection from [x]; this does leave color spray and similar effects, but the main "theme" of conjuration and enchatment is all but negated in combat by this spell. And we are talking far higher spell levels; a 1st level spell that protects you from summon monster IX, dominate monster, and more. That, to me, is an imbalance in the rules; the protection from [x] spell is unbalanced. Adding a +2 to AC just adds insult to injury.
Don't get me wrong, those spells are still great when your foes aren't prepared, and when they are you should have other options. But for example, my group recently met with a diviner; intelligent and well-prepared, he knew they will try mind-affects and prepared accordingly. His minions had protection from good potions. Those suggestions aren't working as planned all of a sudden. And if they were not working with the XPH, their summoning spells wouldn't have worked too. That's two characters' main strategies completely neutered by a 1st level spell, when the characters were at 6th level. Plus his constructs are immune to mind-affecting spells to begin with. Sigh. Anyways, I just think protection from [x] is way too powerful.
And when you do get to high level, you get mind blank...
Mind Blank
Duration: 24 hours
The subject is protected from all devices and spells that detect, influence, or read emotions or thoughts. This spell protects against all mind-affecting spells and effects as well as information gathering by divination spells or effects. Mind blank even foils limited wish, miracle, and wish spells when they are used in such a way as to affect the subject’s mind or to gain information about it. In the case of scrying that scans an area the creature is in, such as arcane eye, the spell works but the creature simply isn’t detected. Scrying attempts that are targeted specifically at the subject do not work at all.
By definition, then, mind blank protects against ALL enchantment spells. That's it, you are completely immune to an entire school of magic (and a few other spells, and to divination too but that one is supposed to be weak). To the best of my knowledge, no other school (sans divination) suffers the same fate. This, to me, seems to yet again be an imbalance in the rules. Not only that, it isn't a great idea either - if we allow, say, a suit of "Blank X" each protecting from one school of magic (plus divination), we would cause the game to become duller, as more and more spells will be completely foiled. A person could walk with a few of these and be all but immune to magic - which is not balanced, even for multiple 8th level spells, and what's more important is not fun.
Now to illusion.
Detect spells foil the idea of hiding or disguising stuff with magic. That's a key idea of the illusion school, and it is pretty much wrecked with a simple detect magic. Yes, a rouge can sneak attack with greater invisibility. Great. Except arcane sight lasts longer (and often made permanent; it's just cool), is one level lower, and instead of making the rouge invisible the greater invisibility now hangs a big sign over him saying "rouge guy here!". Not to mention illusionary wall, or disguise self, or even veil. Instead of hiding stuff, these spells say "hey, something's fishy here...". Really, a smart wizard, especailly at high levels, will put an illusion only to have it be seen - since it will be.
Now illusion isn't as useless as enchantment. At low levels there are plenty of uses for when the bad guys aren't throwing detect magic around, or if they are there are cases where the spells are obviously magical (I am playing an enchanter-focuses sorcerer, and color spray is great). Even at high and mid levels true sight allows a few spells to slip by (blur won't work, but phantasmal killer will). Overall, however, I just think it makes the illusionist concept unworkable from mid levels; a party facing off one will always have someone use arcane sight/true seeing, and that will be the end of it.
The expanded psionics handbook has a level 2 power that provides you with power resistance against mind affecting effects. I think that's a good idea. Spells shouldn't void entire schools or subschools, or make them redundunt.
Anyways, that's my view.
Yair out.
