The first question many site designers and business owners ask when confronted with accessibility requirements is "Why?". That's a reasonable question to ask, and an easy question to answer. The reason is simple. There is a significant portion of the population with disabilities. According to The Center for an Accessible Society
there are over 49 million Americans living with a disability of some type, with over 30 million between the ages of 21 and 64. That's nearly 20% of the population or 1 out of every 5 people.
Even with nearly 20% of the population having some type of disability, many corporate web sites simply ignore some of the most basic accessibility guidelines.
Many companies and web site owners do not fully appreciate the impact of making a site non-accessible. Imagine if your local WalMart or Target store had a greeter that told every fifth person to leave because they didn't want to make their store accessible. That store would be in big trouble, not just legally, but financially as well.
One of the most common defenses against making a site accessible is that it is either too costly to do, or it is to complex to adhere to the guidelines.
The former of these arguments is difficult to justify because simply saying "no thanks, we don't want to help you" to up to 20% of your visitors can't be good for the bottom line.
To summarize, accessibility matters because it makes for a better user experiences for ALL visitors to your web site, and because if makes business sense.
Till next time.