Talking of weird UIs, what possessed the maintainers of the Xubuntu pdf/document viewer (Atril) to put the "File" and "View" menus top right instead of top left and give them both the same cogwheel (ie "Settings") icon?
And while I quite like the ribbon interface in Word, why does "File" bring a huge clunky side bar menu into play instead of just changing the ribbon like everything else?