Aero was peak aesthetics. Flatcrap became commonplace because it was easy. No need for designers, just flat colors, resizable to fit any screen. Perfect for mobile slop!

Was Aero also the last instance where all of the Control Panel widgets were actually Desktop first? Ever since, they Control Panel has been a mismatch of Mobile design and being limited to a single interface pane. It is maddening to look at the historical data density that was tossed for something a programmer could thoughtlessly bang out in an afternoon.