It's possible to get so caught up in following the rules of web accessibility that one can forget the simplicity of plain old visual accessibility and those it affects. Before I continue further, here's a warning: this topic reaches deeply into the Camp One "accessibility for all" aspect of web accessibility. Okay, that said, I will make mention that the vast majority of your site's visitors are of the sighted, mouse-using, up-to-date-browser, JavaScript-enabled, Flash-equipped variety. As a disclaimer I will say this is a hypothesis on my part, but I'll betcha five bucks it's true. And, coincidently, it is this very user-group that will benefit most from visual accessibility. That makes it important.