consider this a rough version of my thoughts on accessibility and the reasons why. hopefully will fill out as I go.
The worst reason: lawyers
The law in some countries is very clear on Web accessibility. (At least that it’s required, whatever the standard itself may look like.) The United States isn’t one of those countries. If you’re a federal government agency, it’s clear: Section 508. But does 508 apply to other sorts of things that get federal money (like state agencies, schools, non-profits)? Maybe. Does the ADA apply? Maybe.
But that’s a crappy reason, anyway. Here are some better ones:
Google will like you better
Most of the things that get in the way of visually-disabled people get in Google’s way too. Add alt attributes, don’t use frames, make JavaScript unobtrusive: better for both.
Get the benefits of standards
“Web standards” and accessibility are often found intertwined, and with good reason. It’s easier to make a page accessible if it follows standards. Using valid code has some interesting benefits of its own: done well, it’s easier to maintain and saves bandwidth.
(Usually) make it more usable
Many specific techniques that are suggested for accessibility also make your site more usable in general. (no “click here”, clear difference in link color, clear writing) Sometimes the goals of usability for the non-disabled and accessibility for the disabled are in conflict, but those tend to be edge cases.
Do the right thing
If you incorporate accessibility at the beginning of every project, then it’s not (usually) any more expensive, so why not? (There are edge cases, mostly revolving around multimedia.) Would you be such a jerk as to not hold open a door for someone who had both hands full? Then why slam the door on someone who wants to use your site?
For non-profits and schools, it’s not just a matter of being polite; our missions are to serve, in whatever capacity. Our values are (usually) inclusive. Having an accessible website is an opportunity to live our mission and values.
Warm and fuzzy, efficient and effective: plus if the lawyers ever knock at the door, you won’t have to break a sweat. Sounds good to me.
Joe Clark also talks about reasons to go accessible in his excellent book…
Once you learn accessible design techniques, you heighten your sophistication, and may then stand taller in the saddle. ?You mean you don?t know about accessibility?? you may archly ask your inferiors, rolling your eyes and sharing a knowing grin with your compadres.