What makes a GUI feel modern to me these days is less about the "looks" and became more about the "feel". This means how I interact with the application, the way navigation works, the way I manipulate the view and the content.Coming back to this old thread, could everyone post 5 design points they think should be in a gui going forward. Try to forget legacy homescreens or referring to xbmc skins etc and think of a skin design going forward something modern.
Too feel modern, the UI is required to be really fast and responsive, otherwise the most modern "looking" GUI will end up feeling clunky and old.
And this brings us back to an ancient issue of MP - the speed (and overall limitations) of the engine.
Concepts like dynamically altering a list by fluidly "swiping" an item out of a list and things like this which make the GUI feel fresh and modern are just not possible in the current state.