Keeping stuff on the desktop is a bad idea for a wide variety of reasons. I just wrote a lengthy post on the topic so I won't repeat it here. I think that wallpaper's rather clever, but OS X just isn't designed for that workflow. You could easily put the Downloads folder in your Dock to perform EXACTLY the same function (ditto the other "categories").
Shop for your Apple, Mac, iPhone and other computer products on Amazon.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.