Because one of the principal designers of Windows 8 liked print design and thought computer UIs could learn from its literally centuries-long history[1]. I can’t even say he didn’t have a point (in particular, the “wasted space everywhere” cries don’t really provoke that much sympathy from me—waste, yes, everywhere, no). But it does indeed not seem to be working out for conventional KVM interfaces and not even that well for touch.
As a side note, Google’s Material Design (mentioned in neighbouring comments) actually had a fairly detailed physics (metaphysics? metaphorical physics?) worked out[2] in the first version, but the second regressed to a list of widgets and metrics, and then the everything-is-flat current one arrived.
Everything is just slow, slow, slow. Gotta hunt around for the window border instead of seeing it. Gotta hut for the edges between buttons. Gotta hunt for where the title bar becomes the window content. Gotta try to scroll every list because you can't immediately see which ones continue beyond the visible area.
As a side note, Google’s Material Design (mentioned in neighbouring comments) actually had a fairly detailed physics (metaphysics? metaphorical physics?) worked out[2] in the first version, but the second regressed to a list of widgets and metrics, and then the everything-is-flat current one arrived.
[1] https://web.archive.org/web/20120314071640/http://kruzeniski...
[2] https://m1.material.io/material-design/material-properties.h...