Originally Posted by
Necroticplague
AC isn't worthless when it's actually used, the problem is that it has a binary nature (to make it worthwhile, you either invest large chunks into it, or you dont bother), that it is easy to get around (Oh, wow, you have an AC in the high 70s. My DFA,sorcerer,beguiler,warmage,swordsage,DN,dragon shaman,shadowcaster,and truenamer dont really care). The best way to avoid damage is to make sure the enemy is dead before they can attack you. Plus, AC is relative to the AB of what you're fighting, while other defenses are usually flat chances regardless of opponents (Oh, wow, an AB of +70? My cloak of minor blur still blocks 40%, while an optimized AC might not do anything).