Is Web Accessibility important and why?

You should always care about it. It's an issue that will never go away; until the medical world can regrow limbs, restore vision, hearing, learning disabilities; which won't be in our lifetime likely.

Any good design will take into account people with any sort of ability or disability, of any nature, and any limitation. Sounds overwhelming doesn't it? It is. However, there are best practices out there for the web that should be followed, and will help you.

The essence of any good design will account for these issues. Don't worry, design in print, media, and product or industrial face similar issues creating great designs too!

The good news, people with disabilities are so use to everyday things being so much more difficult because so much of world's design as completely ignored their ability to function with their disability, that even a small amount of accessibility work on your part, will really make your website, product, or service stand out above the rest. It'll be a welcomed relief to them.

For those of us who are considered "normal" (I use that term loosely), we'll never know the difference.

Yes. To me good web accessibility is extremely important. I have ADD which makes it complicated for me to actually maintain my attention for websites if the web accessibility is bad. You should really care about this and the rest of your "audience", so to speak, that are affected with ADD.

I'm able to concentrate on the TTH videos, quizzes and challenges because, well, they are colorful, and really just.. uh.. catch my eye. And the site is very accessible.

I hope this helps. :)