I'm always impressed with how the Mac menu bar + Apple menu has remained in the same place since 1984 [1], performing pretty much the same functions for over 30 years!
Compare that to the lack of concrete UX decisions in the world's other major OS, unable to settle on a single menu style and so much flip-flopping on key features (cough-Start Menu-cough); removing them in one version and bringing them back in the next.
Is the Mac OS Menu a design that simply cannot be improved on, or are the users just not clamoring enough for a change?