![Small Confused](images/smilies/smallstick/smallconfused.gif)
But Celia isn't an airhead? She's naive with regards to harsh realities of lower class life (and, y'know, mortals) but she's not
stupid. She's an excellent lawyer, in fact, and her antagonism (using your definition of it) was that her rather developed moral code didn't condone murder.
In the meta, this-is-a-representation-of-a-game, reading of OotS, she's the character who doesn't want to kill the Kobolds when the rest of the party just wants to get on with the adventure. Not necessarily a bad thing, but I'd say a lot of people have had annoying experiences with that kind of character, and that's why she gets that bad reaction. They consider her actions to be stupid, but her to be smart, so her 'stupid' actions annoy them, on top of the D&D action.
I actually really, really like Celia, though, and find Miko...interesting, and pitiable.
Also Miko was definitely as much of an antagonist as at least Nale - I'd say moreso. I think you're being unfair here.