Accessibility for the disabled is important. But since the theme here is to encourage design that doesn't presume the audience to be like the designer (probably

Accessibility for the disabled is important. But since the theme here is to encourage design that doesn't presume the audience to be like the designer (probably educated urban middle class and up young adults), I'd like to add "different culture, education level, socioeconomic status, and age" to the list of things that designers should be aware of. As someone who deals with such people quite often, I can say from experience that the disabled are far from the only group that modern digital design excludes.