I really wish they'd get rid of that awful 'ribbon' in the file explorer. It's very practical in Office applications, but for a file explorer it's just a bit too much, imo.
The ribbon can be hidden so it's not too bad. The interesting part is the reason why they chose to introduce it in explorer. There was a Microsoft study (can't find the link atm unfortunately) which showed the majority of users couldn't cut and paste or 'select all'. The Ribbon is meant to expose more functionality to the end user which I guess us keyboard shortcut users take for granted.
It'll be interesting to see if it achieves that goal. In my experience of watching my parents interact with a computer too many buttons translates to "complicated and scary". I think a more reserved approach might have been a bit better than the nuclear option of bombarding the UI with as many buttons as there are options in the current menu.
I have difficulty believing such studies, especially since I could copy & paste files in Windows Explorer, using the mouse right-button shortcuts, ever since my parents got me a computer in 1995. I also do not live in the Valley or in the US for that matter, and having non-technical friends down here is the norm, rather than the exception. I have never seen one that could not cut/copy/paste files in Windows Explorer.
The only thing I noticed is that some people don't understand the difference between "cut" and "copy", or why the mouse drag&drop sometimes produces the former, while other times it produces the later. But these are separate things entirely that can't be solved by ribbon shortcuts.
Having worked at a library providing computer tutoring and assistance, I can absolutely believe such studies. You say "using the mouse right-button shortcuts" - the vast majority of people don't know these exist, or if they do, no idea how to use them (or what a "context-sensitive" menu is). When I guide my grandmother through something over the phone, I often have to specify whether she needs to click or double-click something - which I find so obvious now as to not even think about. Go figure.