A couple of points: first, none of these ideas or vaporware products are doing anything to prevent anyone from using the web the way they want to. You can still buy a new computer, install Firefox, and type in a URL. I would be somewhat more worried if, for example, Microsoft made it impossible to type URLs into Internet Explorer, but that's not the case. (And even then, as long as other browsers exist, it's not that big of a deal.)
Secondly, I doubt the author has worked with the "average" computer user all that much. I do, every day, as an IT consultant -- whether with individuals or employees of large or small companies. The great majority of them don't know what the "address bar" is; if I ask them to go to "www.google.com", they click on their homepage -- whether it's yahoo or iGoogle or what-have-you -- and type "www.google.com" into the search box.
These companies are trying to serve a market, and it's a very real -- and very large -- market of users that don't know an IP from a URL, and they definitely are confused by this stuff.
Hell, one of my clients was furious with me because every time she clicked on her email address on the new website, it opened up Outlook Express on her computer, and dammit, she uses Gmail...