> As long as there have been GUIs, platforms have issued style guides to developers and expected them to emulate the look-and-feel of the platform's own OS and flagship apps.

There's a difference between having a platform-specific GUI/style-guide (which I support), and changing it every few years for no apparent reason (I understand e.g. the change from Apple OS 9 to OS X - they were simply catching up with the hardware improvements - but OS X to OS Y(osemite) seems quite arbitrary).