From: Ed http://www.cs.utexas.edu/users/EWD/misc/vanVlissingenInterview.html

As to the programming products that are used by people, I hardly have first hand experience, my impression is that an enormous amount of user time is wasted figuring out what the system does and how to control it, which is the consequence of two sorts of happenings. First of all that the designers have failed to keep the interface of a system as simple as possible—which is a challenge; but as soon as you realize that the main challenge of computer science is how not to get lost in the complexities of their own making, it is quite clear that this is a major task.