There are some substantial benefits of accessible web design and development:
It makes good business sense: Who would want to limit the amount of their product or service that they can sell? Not many, or if that is the case then they will not be in business for long. Building accessible websites can actually increase the amount of business you do by ensuring that no one is excluded from your website. So effectively you allow anyone who is interested to enter, treat them well, and ensure that their stay is a pleasant one.
Enhanced SEO (Search Engine Optimization): SEO can seem to be a black art (and for some it literally is). If you are a little unsure of what to do to get your business-website ranking improved don't fear—make your site accessible and it's ranking will certainly improve. This is because search engines (including Google) can be thought of as blind users. If you structure your content well and make it accessible—then search engines will be able to search your content more quickly, find appropriate keywords, and serve your pages with a higher ranking for relevant keyword searches.
Note
Search engines like Google often change their secret algorithm, and many try to anticipate these changes, and hack their HTML accordingly. This is a waste of time.
You will be much better off creating a nice accessible site rather than performing keyword stuffing, abusing alt tags, and other bad, black hat SEO practices.
Better design: Graphic designers unfortunately, often design for themselves. This is not always the case, but is often true. As a result the Web is littered with sites that use tiny text that can't be resized, illegible fonts, and bad color contrast. This often renders the site content unreadable to many—though in the designer's head it looks great.
So by considering the diverse needs of users, for example, people with vision impairment who need good color contrast and resizable text, the designers should change their styles to accommodate these user's needs. A good design principle is that "form should follow function". This is a simple, but effective mantra. Unfortunately, it is often completely ignored.
Note
Accessibility brings some important design issues back into sharp focus and designers must rethink how they are going present content, their layout techniques and so on.
How you design can have both a powerful positive and negative impact, so don't just follow fashion, think about your users.
"Accessibility is not anti-design". Many of your cool graphic designer friends might believe this. They are laboring under a misconception. Accessibility actually forces them to think about the details and motivation behind what they design, forcing them to not vainly follow trends, or use their design skills only to express themselves.
Tell them if they wish to express themselves they should join a punk band, otherwise they should think about what they are doing and ensure that lazy or shallow fashionable design styles do not dictate how they work.
If you have an awkward client who refuses to see reason when it comes to good design, firstly take a deep breath, and try explaining the reasons for your design decisions. This means with careful use of logic and good reasoning you can usually beat any fuzzy ideas your client has about their perception of what constitutes a good design.
