Because the UI needs to match the device

This is really cool.  Tablets are awesome, but tablet UI design is just in its infancy right now.  New tech is always first defined in terms of the old.  Cars were horseless carriages, aircraft measure speed in "nautical miles," etc.  It makes sense that the first tablet UIs would be built based on desktop computer knowledge, but it's good to see folks recognizing that and starting to move beyond.