It feels to me that the problem isn't so much the the total cognitive load/friction of a user interface, but the kind of thinking an interface demands. In order for an interface composed of high-level abstractions to be something that we can tinker with, it has to be a system that follows logical rules that can be easily inferred, and those rules have to be Turing-complete. Once you have formed an accurate mental model of the software, you can use it very efficiently with a low cognitive load.<p>But ordinary, everyday people don't want to infer how a system works. They don't want to think scientifically, and they won't invest any effort in building a mental model of how the device really works. Instead, they want the device to conform to the mental model they cobble together on the fly - logical consistency be damned. They have no curiosity to learn how to fully use the tool (or else what little curiosity they have is overwhelmed by the frustrations of the software violating their expectations). If they did, they would be programmers, because anybody who understands how computers work will end up using that knowledge to make it do something new. (The power and possibilities of a programmable machine are irresistible to anybody who actually comprehends it, but first you have to overcome the initial task of understanding how the machine computes. And to continue as a programmer, you have to tolerate the frustrations of the leaky abstractions.)<p>If you want a user interface that can be used without any scientific thinking, you have to restrict it to a finite set of capabilities so that you can anticipate what the user will try to do. But at that point it is no longer really a computer: it's a shiny toolbox. You can't make new tools with it; you have to buy them at the App Store.<p>The problem of users being unwilling to think analytically isn't one that Apple can overcome. I doubt that any for-profit corporation can do anything about it, because it is a broad cultural and generational problem. Computers haven't been around long enough for us to know how well the general population will eventually adapt to using them, but it's a sure thing that without true AI, people have to adapt their ways of thinking in order to use the full power of computers. Until then, people will keep wondering why we programmers can't manage to give their Photoshop an "enhance" button that works like the ones they see on TV.