Advice for Developers: Make Common Usage Easy
Ken Hendrickson writes "Thomas Sowell has some fantastic common-sense advice for software developers from the viewpoint of an ordinary user: Make it easy to do what almost everybody wants to do. I don't believe he uses Free Software; that means that Microsoft is not satisfying their customers, and Free Software can perform better than Microsoft even in the ease of use area!"
read "The Inmates Are Running the Asylum : Why High Tech Products Drive Us Crazy and How To Restore The Sanity" by Alan Cooper.
This book clearly and succintly states the difference between how programmers and engineers design (for the edge case), and how people really want things to work (make the common cases easy.) An excellent book, it could be used as a textbook but it's too short. Go read it.
Both are excellent reading for those interested in the art (science?) of good UI/usability design.