"It is possible to design very good, if not optimal, systems with zero user feedback. Many things - from great works of literature, to great art, to innovative software, have been designed this way."While that is certainly true, educational technologists and designers are not creating works of art for their own amusement or self-expression. They're mostly trying to create web sites, learning objects, software or other resources to help people teach and learn things.
It seems to make sense that we would design better learning resources if we found out why people wanted them in the first place, understood the context for their use, and tested prototypes to make sure the intended users could actually accomplish their goals. This is pretty basic instructional design methodology, but my main point was that these steps often get glossed over because they're more difficult than just designing in isolation.
Stephen actually found a great example of this problem in a recent post: Library Terms Evaluated in Usability Tests and Other Studies. A library created a web site for students to access online journals and other library resources. The designers of this educational site were probably skilled enough. They even got in contact with a librarian (better than working in a total vacuum), because the terms they chose as navigation labels tended to be library terms. But the students didn't understand them -- many expected something else when they clicked on a link. If the designers had done some prototype testing with students (even just a few), they could have come up with a much better learning resource.
It's true that decent systems can be designed without stakeholder participation or feedback. Most of us would love to believe that our assumptions are at least close, and that the decisions we make about designs will help people accomplish their goals. But very few people get it right the first time. Skilled designers are almost always shocked the first time they see the results of usability studies on their work. Our first instinct is to blame the users for their inability to understand the most obvious navigation or complete the simplest tasks.
As educational technology develops, and online learning becomes more prevalent, user experience will become more and more important. People will expect their courses, learning environments, and digital resources to be as easy to use as the best e-commerce, games or communication tools. Users might not give us the magical inspiration for a better way to learn, but they can usually tell (or show) us where our designs aren't working.