Now that computers are ubiquitous in the our culture, I think that people have forgotten how non intuitive graphical user interfaces can be. Twenty years ago, an "introduction to computers" class or video would focus on how to interact with menus, open and close windows, and how to use a mouse with more than one button. If you want a good laugh, search YouTube for introductory videos to Windows 95.
I've found that people that are uncomfortable with computers have problems with flat design, often because it is harder to for them to find buttons. It seems like a trivial thing to people who are comfortable surfing the web, but for those who are not, it makes for a frustrating experience.
On another note, I found it curious that the author didn't mention Microsoft Bob and the other contemporary "real object" graphical shells.
I've found that people that are uncomfortable with computers have problems with flat design, often because it is harder to for them to find buttons. It seems like a trivial thing to people who are comfortable surfing the web, but for those who are not, it makes for a frustrating experience.
On another note, I found it curious that the author didn't mention Microsoft Bob and the other contemporary "real object" graphical shells.