We'll have to agree to disagree about that. The flat colored circles at the top left corners of windows don't look like buttons to me. And the OS is chock-full of clickable text that is visually indistinguishable from non-clickable text, and hidden controls that only show up when you hover over a magic area of the screen, again with zero visual cues that there is anything there. I like a good easter egg as much as the next person, but not when finding them is actually crucial to getting things done.

There may be some widgets that still look like buttons, but that's not what I'm talking about.