Annie must really, really want to be in the Seven/one of the Seven. Sure, her new costume looks great and all but she preferred her old one more. Not only that, she was subtly threatened into going along with it because she'd no longer be one of the Seven if she didn't. Something even worse than what The Deep did to her has to happen for her to no longer care whether or not she's one of the Seven. I'm just not sure whether that something will happen.