They tried once - they released interface guidelines with Vista and for a while it worked but soon they started to flip everything over as usual. W7 was relatively a polishing up release but they mangled everything with W8 - not only because it didn't had Start button but also because they tried to combine Aero with Metro and it just look awful. It's hard to not see similarity in Apple's Liquid Glass on top of flat elements from previous releases.
All in all, Windows still comes with that 90s-early 00s flat 9x widgets buried deep beneath fancy W11 interface for compatibility reasons. Because Microsoft never could have their OS9 to OSX transition equivalent. They swapped DOS based 9x line but interface was still same - hell even NT got sprinkled with 9x and dropped old 3.x one
All in all, Windows still comes with that 90s-early 00s flat 9x widgets buried deep beneath fancy W11 interface for compatibility reasons. Because Microsoft never could have their OS9 to OSX transition equivalent. They swapped DOS based 9x line but interface was still same - hell even NT got sprinkled with 9x and dropped old 3.x one