I do find it a little amusing that some people use the tilt feature of the sunroof just for the look or style of it. The function of the tilt feature is clearly to vent the cabin, which is why the shade only closes about 3/4 of the way when the sunroof is tilted.
I know someone mentioned that VW's and Audi's can close the shade with the roof tilted because the shade has integrated slots for ventilation. I prefer BMW's design over this though, because I would probably forget all the time that the sunroof was tilted if I could close the shade all the way.