Using a command line interface is like having to learn Korean to order food in a Seoul branch of McDonalds. You can see the minimum-memory principle at work in features like auto completion, too. Users can't remember anything You might be starting to get the impression that I think that users are dolts. It's not true. This kind of chutzpah is pretty common in the free software world.
Human aptitude tends towards the bell curve.
So, I don't really believe that people are dolts, but I think that if you constantly try to design your program so that it's easy enough for dolts to use, you are going to make a popular, easy to use program that people like. And you will be surprised by how what seem like small usability improvements translate into lots more customers. One good way to evaluate the usability of a program or dialog you've never seen before is to act a little stupid. Don't read the words on the dialog. Make random assumptions about what things do without verifying.