It does serve a purpose...keeps that left rear cargo door striker plate from striking the exterior paint of the right rear cargo door, should an accident happen.
Mine popped off at only 4K and I was perplexed for a bit too. I drilled through the piece and the plate, and attached it with a small oval head bolt and nut. I realized it's function when the head of the bolt lightly hit the right door when I had both semi-closed ...eventually I will replace the bolt with a type having a plastic head, perhaps like a chair-leveling bolt.
