It seems to me that the constant "overhaul" of a GUI to change icons, menu structures, etc is bad design. Not because the final product is necessarily bad, but because whatever improvements the new design brings are dwarfed by the cost of throwing away of user knowledge about the old interface and the cost of re-learning a new interface and its symbols and structure.
There's probably even unconsidered effects. A lot of clients I've worked with have resisted upgrades (they own and have paid for) to Office because of the radical changes in look and feel. By running older versions with weaker security, they're now exposed to greater risk of compromise by malware. There may even be meaningful losses in productivity from missing new features or improved implementations of existing functionality. This can even be made even worse by resisting operating system updates.
I've always been puzzled that some of the best minds in user interface design get together and say "obviously, the best solution is to throw out everything the users have learned and give them something totally different."