As someone responsible for staff training and support, I'm painfully aware of this. For this reason, I've paid more and more attention to the CMS development process. And it's been for partly selfish reasons - the poorer the usability of the CMS, the harder the job of our training and support teams.
(Some usability enhancements I helped introduce to the University's CMS made it into Jakob Nielsen's Usability ROI case studies.)
Here, Karen McGrane (Content Strategist) and Jeff Eaton (Drupal CMS Specialist) talk about how to make your CMS more CMS-user-focused. They're talking to a Drupal developer audience, but I think the approach they recommend applies equally well to any CMS.
Presentation & audio - Baby Got Backend: Content Administrators are Users Too by Karen McGrane and Jeff Eaton (Skip to about 8 minutes in for session to start. Ignore the wasp in a jar.)
Slides on Slideshare - Baby Got Backend: Content Administrators are Users Too by Karen McGrane and Jeff Eaton
Related stuffJeff Eaton's follow up presentation - Baby's got backend: the sequel
Previous post: Does your CMS support your content strategy? (September 2011)