It's a shame that this chapter is as short as it is. Accessibility is very important, and for good reason: Unless we take accessibility seriously, too many people with disabilities will be unable to use our designs.
When doing research into the benefits and principles of simple design, accessibility didn't come up very often. Perhaps this is a reflection of how far we still have to come.
When I emailed Jonas Downey at Basecamp to ask about the principles behind their simple design, and especially their colour choices, good accessibility was one of the reasons:
[Colour is important for] accessibility ... lots of color schemes are problematic for people with vision impairments or color blindness, so it's often better to keep things as simple as possible to remain accessible for everyone.
The Web Content Accessibility Guidelines (WCAG) lay out the requirements that websites should meet in order to be considered accessible. Many of the requirements focus on making sure that elements are clearly described, and that non-text elements have text alternatives.
Simple design's focus on putting content first is a natural partner for accessible design. If you have fewer elements in the first place, it's even easier to provide alternatives for what remains.
Here are some of the accessibility principles listed on the WCAG website. If you've read the book up to this point, they should be familiar: