[MWinther]

Exactly. Getting a working mental model, even if it's not very exact, does wonders for the ability to experiment. The problem is, most people get an explanation of what the different parts of the computer are, but not a working model of how it works.

And here lies the challenge of designing computers that are useful for people without the mental model, and efficient for people with it. Gadgets tend to do one or the other, but accomodating both is a good bit harder.