Wouldn't this be useful in this scenario:
1.) Open a full screen application.
2.) Press the Windows Key + Spacebar to use desktop peek.
3.) Try to click anything on your desktop. Yeah... you can't.
But wouldn't it be useful if you could? You could access something quickly and easily on your desktop without having to minimize your application(s), click what you want, then maximize the application again. Nice feature, don't ya think?
Allow us to click through the desktop peek glass to the desktop.