alert. I'm going to be bullshitting
you from this paragraph on.
Ignore the previous paragraph. Everything I say is true.
Everything is an interface. From the persona you adopt at work, the money you have in your pocket, to the social pleasantries you use when talking to strangers -- they are all functionally described ways of interacting with something that isn't you. Arguably they could more accurately be described as protocols, but the point is that a good part of life is codifed in ways which are so pervasive we usually don't notice them until the interface changes in some way, typically when we go to a foreign country.
It's the lack of comprehensible social protocols which makes living in a foreign country so intimidating. There as few things as alien as watching people who exist perfectly well without things you feel are as natural as breathing.
The issue I believe Johnson is pointing out is that society has advanced to the point where it is totally enmeshed with machinery, to the point where society as we know it would have a nasty shock without computers, email, the internet and cellphones, depending on how you define society).
But because these machines are continually evolving and being replaced, along with the interfaces used to interact with them, people have to be able to constantly learn new interfaces in order to keep up. A few years ago, nobody understood the internet and computers were for geeks. Now, kids are considered uncool if they can't hack their way past their parents' censorware. Being able to learn new interfaces (of whatever kind) is considered a vital skill.
A good part of this phenomenon is attributable to the Web. The first web sites were very simple hypertext pages. It took the creation of forms and SSL to make the web into something that people would actually use.
Hence, many web sites, all producing dynamic pages, mostly known as web applications. There are HTML interfaces for doing mail, sending invitations, chatting, buying books... every single web site is a new application with its own interface which must be mastered.
It took a while for people to get used to the idea. How often did people buy stuff off the web in the early days? In spite of the fact that many people are computer literate, most users don't deal with new applications on a frequent basis. Despite that, the browser platform allowed for an explosion of new applications, all startups,
all with an idea which they thought the public would want. Of them, the most successful was probably Amazon. Jeff Bezos created a web site which not only sold books, but which fostered an online community which discussed and recommended those books.
The opportunity to communicate to people will overwhelm any qualms about using a new interface. In any medium, cheap communication between two individuals is a total killer app. This explains why the telephone, instant messenging and chat are so popular, along with message boards and usenet.
New interfaces continue to crop up all the time. Look at slashdot or everything -- look at the palm pilot and the rise of the new wireless internet phones. It's only a matter of time until John Carmack provides an engine powerful enough to act as a crude metaverse... and everyone will just have to keep up.