>To take Mekantos's side of things, why does a potential staff
>member need to demonstrate the ability to churn out an area
>file if:
>
>1. He's already shown a grasp of game mechanics.

Because many people who think they do have a grasp...don't.

>2. He's already shown exceptional ability to role-play.
>3. All he's going to do as a staff member is run quests and
>provide mortals with IC interaction?

Because that's not all you are required to do.

>Is there a downside to having allow certain staff to exist
>with a very narrow focus?

If you have a subset who get to focus entirely on the roleplay and zero on the administration side...why wouldn't everyone join that subset? I know I don't do the administrator part because I enjoy it.