Why Mess With The Dust Cover?

An interesting article, and redesign of a component of your Modern Sporting Rifle that is often overlooked, and neglected.  Go read it, and then take a look at what these guys are doing.  They have approached the problem with some logic.  The base question that comes to mind though, is why did Stoner design it the way that he did?  Was it cost, reliability, or an afterthought?

I see some research in my future.