Pride and commitment
Most of this discussion has been based on extrinsic reasons for wearing a hakama. How do others view you and your rank, a sense on unity with your dogo, rank, achivement, and etc. But aikido training is much more about intrinsic (inner-self) than what kind of attire you wear on the mat.
Being a member of my dogo (ASU), the hakama is encouraged by all students regardless of rank. And by this, the hakama is somewhat of a non-issue. In my opinion, the hakama is nothing more than my commitment to the art of aikido...nothing more.