Engineers need to understand how the mind works
I like this point of view of Pinker (From Edge 3):
Computer technology will never change the world as long as it ignores how the mind works. Why did people instantly start to use fax machines, and continue to use them even though electronic mail makes much more sense? There are millions of people who print out text from their computer onto a piece of paper, feed the paper into a fax machine, forcing the guy at the other end to take the paper out, read it, and crumples it up—or worse, scan it into his computer so that it becomes a file of bytes all over again. This is utterly ridiculous from a technological point of view, but people do it. They do it because the mind evolved to deal with physical objects, and it still likes to conceptualize entities that are owned and transferred among people as physical objects that you can lift and store in a box. Until computer systems, email, video cameras, VCR's and so on are designed to take advantage of the way the mind conceptualizes reality, namely as physical objects existing at a location and impinged upon by forces, people are going to be baffled by their machines, and the promise of the computer revolution will not be fulfilled.
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[…] [The problem is that the] machines were designed by engineers that aren't used to thinking about how the human mind works. They're used to designing machinery that is elegant by their own standards, and they don't think about how the user is going to conceptualize the machine as another object in the world and deal with it as we've been dealing with objects for hundreds of thousands of years.