My apologies for nit picking, but It was actually Office 2007 that introduced the "ribbon" interface and "Microsoft Office Button" that replaced the File menu.
Office 2010 replaced the button with the "File" tab that opens "Backstage" where Save, Open, Print, etc. options are located.

Cosmetic changes such as these remind me of when American auto makers used to change the front grill and head and tail light lenses from one year to the next to differentiate a particular year of the same car.Everything else -- body, frame, engine, interior -- would be the same.

I don't know that the ribbon was an improvement but it has undoubtedly sold a lot of books, training materials and classes. Perhaps new users learn to navigate the ribbon easier than the old menu & toolbar interfaces.

For existing users, such changes incur a great deal of lost productivity while they learn the new interface. Hopefully, they may learn to take advantage of both new and existing features that may provide shortcuts and increased productivity in the future.

And there will always be complaints about changes in user interfaces. While writing character-based applications in the 80's, when an item was added to or removed from numbered option menus, users would complain that they "have always pressed 2 then 5 then 12" to do such and such "but now it is 2 then 5 then 13!"