We are all here because we care about usability and Drupal. I think it is important for the rest of the project that we are able to articulate why.
Thes following discussion should be edited down to a concise piece of text which can be part of an introduction to usability for people concentrating on other fields and Drupal.
I used the following quotes as talking points in my recent presentation in Brussels
As content management systems become more alike in terms of critical functionality, ease of use will become a key differentiator (rather then functionality).
Dries Buytaert, Complexity is a disease
Small things add up -- if there is an option in the interface that people have to think about for only 2 seconds (which is probably low) across a million users that's 23 days (555 hours) of time lost to the world!
Matt Mullenweg, Should We Have Hidden Options?
Everyday tasks are not difficult because of their inherent complexity. They are difficult only because they require learning arbitrary relationships and arbitrary mappings, and because they sometimes require precision in their execution.
Donald A. Norman, The Design of Everyday Things, p216
There are plenty of other websites available; leaving is the first line of defense when users encounter a difficulty.
Jakob Nielsen, Usability 101: Introduction to Usability