@david_chisnall Although I get your point, you seem to miss a very important thing: there are lots and lots and lots of people who simply *can't* go beyond natural language. I know many people with little to no math knowledge who were exposed to computers and modern technologies in their fifties. Would they be able to formulate proper requests, as you suggest? Maybe, after an extremely steep learning curve, lots of tears, sometimes panic attacks and such. Do we want this, say, for our parents? Probably not. At least, I don't. Being a developer myself, I wish my mother had an interface best suitable for her needs.
@menelion
"Language" doesn't have to mean spoken language. Look at old UI designs - most of the key elements carry an obvious meaning, often conveyed through visual means as much as words. This, too, is language. The crucial thing here is that it's unambiguous. Knowing the design elements enables the user to predict what an action is supposed to do and a developer to understand what their users would want to happen. It's become rather fashionable to break that pattern, though...
@david_chisnall