It's an interesting read and I can read this stuff for hours. However, I think he doesn't get his point across well. He gives us a romp through things that are actually available for the OS and it reminds you of how lovely that is; there's nothing sad about that at all. Furthermore, he has a rigid concept of what a user interface can be. First he hints at the fact that one can have a completely different type of user interface, then he shows you more of the same. All of these are derived from the PARC user interface. As people have mentioned, there are also tiling window managers. But there's much more radical stuff too, such as CLFSWM. He could've showed us the Xanadu project, which is an interface focused on linked hypermedia. Also, the article contains an error. It says graphical desktops go back to the '80s, but actually, one was already demonstrated in 1968 at The Mother of All Demos.