Are we reading the same books? She totally violates the law that one sister cannot interfere in the business of another when she orders Moiraine to follow Merean. And she orders Merean to take care of her as well!

And she may think the Rebels were idiots, but she didn't show any signs of following Elaida's orders did she? Not only did she stay away from the Tower, she communicated and cooperated with Rand extensively despite Elaida stating that that is not allowed.

And her avoidance of positions of power only adds to her persona. She clearly cares nothing for the system, and bends the rules to suit her purpose. That this makes her the best AS in centuries only proves how useless the Tower has become.

Cadsuane is the kind of headache most leaders would never want. She is a legend, so simply ordering penance or exiling her is not an option. She cares nothing for your authority, and will call you a fool in public if she thinks you're being one.

As a simple example of this contrast... in KoD, when Romanda sees how the presence of an Asha'man is making the sisters panic, she thinks she'd like to go around slapping sense into them, but does not because "that would just not do". In the same situation, Cadsuane wouldn't have hesitated.