I think the main problem that new users to Linux have is the steep learning curve. The author dismisses user friendliness with the implication that the only reason Linux is difficult to learn is because it is different.
The analogy given is vi versus a standard Windows word processor. I am not disputing that vi is a much more powerful program, but I am saying that it is much harder to learn than Microsoft Word. Using Word, without knowing the keyboard shortcuts, you can use the toolbars to do what you want and in doing so you learn the shortcuts, most of which are printed next to the menu items.
Using vi, without knowing any keyboard shortcuts, you can do exactly nothing. Arguably vi is much better off without toolbars because they take up a lot of screen real estate and would be difficult to implement from a terminal window, but that does not mean there is no such thing as user friendliness. Another problem is the problem of hardware support[1], which the author does not address at all.
Having said that, I will agree with his point that since it doesn't really matter much to (with notable exceptions) most developers what features people not already using Linux would like to see, development is centred around people already using Linux and on more gentle slopes of the learning curve.