I .. don't get how anyone can consider ChromeOS to have a elegant UI.
I have a chromebook for traveling and light web dev work since years .. and it works, because I rooted it and allmost do not have to use the UI(I need the terminal and chrome dev tools). In general it got better, but is still horrible inefficient and not ergonomic. Or did you mean it looks good? Well, maybe, but for me a elegant UI means it does not get into my workflow and can do quickly what I want. Which .. it nativly cannot.
As someone using a Chromebook as my daily driver, not getting into my workflow and quickly doing what I want is exactly ChromeOS's UI. Especially virtual desktops combined with the touchpad: Switching between tabs, going forwards and backwards in history, switching virtual desktops and apps is all done with a few gestures.