Neither of your points are really true: ChromeOS uses X Windows, just without a reparenting window manager. ChromeOS is not Unix 'hidden' under a pretty UI --

Neither of your points are really true: ChromeOS uses X Windows, just without a reparenting window manager. ChromeOS is not Unix 'hidden' under a pretty UI -- neither the filesystem nor the userland are exposed to the user or to application developers. There's no Finder as the main UI with a Terminal in the Utilities folder: both metaphors are simply gone.