It could be that:
- Management is looking for depth or breadth of experience that isn't immediately apparent to applicants, lateral peers, or the guy on the floor;
- There's planned operational changes behind the posting that can't be openly discussed because of the impact on lateral peers;
- Management really does have their collective heads up their butts
- Its personal/political.
If you get the sense that you're not being seriously considered, you should ask why not. It won't likely change the outcome, but at least you'll know if there's something you can remedy for the next time - or if the management at your company are just nincompoops.