You can do all these things. You can have designs that sparkle. You can user test the hell out of it. You can have a simplified User Interface and a sensible amount of self-promotion. But while you shoot for the 80%, there are always people who fall off the list. And people with disabilities are usually on that list.
It's easy to try not to think about it. Because it's already so hard to do anyway, why add an extra level of complexity? Why pull in another team of experts? Why introduce flaws into something you are so proud of?
There are three reasons:
- Legal - If you're the government, making things accessible is the law. Period. I'm still trying to figure out to what extent (if any) this applies to other companies. For us, it's a big deal.
- Money - This one should be enough for a lot of businesses, especially e-commerce sites. Disabilities is an incredibly wide term, which covers everything from people with arthritis, to those who can see, sorta, but with terrible eyesight (a.k.a. "low vision") to more debilitating situations like paralysis. But these folks buy things too. They won't hesitate to go elsewhere, possibly after seconds, if your site isn't accessible.
- Public relations - Certainly if you're a government agency and you get sued by a special interest group, that's something you won't to avoid. But those groups can be very vocal towards private companies that exclude them as well. And the converse is true too - to be able to tout your accessibility credentials can have lots of benefits as well.