Are you a structural engineer?
I spotted this on WebAim’s discussion list and thought it perfectly captured what it is to be a designer of an accessible web site:
“… In other words, one designs a page first to maintain a specific informational document structure across different platforms, visual, and non-visual, and then somehow, one adds the gloss of presentation, (visual, aural, text) afterwards. This is not necessarily trival, because this structural view of information tends to be the opposite of the way most people natually think when designing a web page, and is a habit that may be difficult to learn. A designer of accessible Web pages needs to think like a structural engineer, rather than like an interior decorator and landscaper.”
Terence de Giere, http://www.degiere.com/