OA makes some great points (not sure how his points are viewed as QQ, either), but, having gone back and read:
Dulrik wrote:
I said there are no spellcasting penalties, not that there were no penalties whatsoever. Again, the benefits to stances are all physical. To get those physical benefits, sometimes you are trading in magical penalties. The only reason there are not already magical penalties for aggressive stance is specifically because it doesn't really help casters to use it.
I see that the point of stance is to provide physical advantages and disadvantages. There's a nerf to casting in the defensive, but not a buff, and no affect to casting in aggressive. There's no trade-off for casting benefits, you JUST get the debuff, that's it. That means that stance is more about the physical benefits, than the mental. That is to say, the only motivation for people to switch stances should be physical. If a battlepriest wants that defensive bonus, he doesn't get it for free, just like everyone else.
The only real solution would be Cyra's idea. That is, not just to slap on a casting buff for aggressive, but to give more balance to it as a whole. It sounds like Dulrik wants the benefits of stance to be purely physical, though.
Barely tangential, but - another possibility would be to bring back mood (keeping stance the way it is), but revamp the whole way it's used. Something much more creative and free-form - moods wouldn't be symmetrical, but reflect a character's true psychological state. Peaceful, annoyed, depressed, restless, or any number of other possibilities, all with different trade-offs and somewhat more focused on casting capabilities. Implementation would be hard, but it sounds nifty, at first thought.
While I'm spouting ideas, there should be ways to force people into different stances. Perhaps taunt should pull a person into aggressive stance, or a rescued person would enter into a defensive stance? Maybe even new abilities?