Designing user interfaces is hard. It could take months to do and then another couple to find out that it's not working. All the sudden it's back to the drawing board.
So imagine designing one that's more or less permanent. One that isn't digital, but physical. Imagine designing one that is to be used in a whole country. Then design it for blind people.
I encountered this while in Japan. Most sidewalks in between train stations in Tokyo, Kyoto and elsewhere have specially designed yellow paths leading from one station to another. They lead right from train exit doors and criss-cross the stations, going up stairs, down hallways, up to bathrooms and information booths, and out to taxi stands and bus stops. In Tokyo, most stations are even connected by this network of paths.
The path itself is raised off of the sidewalk in yellow rubber. It is about a meter across with 3cm grooves in it to let the user know that he/she is walking on it. When you reach a corner or a place to turn the grooves turn into circular bumps so your feet (or your guiding stick) are warned to stop, turn left or turn right.
I tried walking it myself with my eyes closed, making sure to have someone nearby in case I walked into the road and got hit by a Toyota. It's hard to walk a straight line (try it) with your eyes shut (especially after a few Sapporos) but once you get the hang of walking with the nubs along the ground guiding you, even rounding a corner was quite easy.
It reminded me just how hard it is to make a good UI that works for everyone, not just the power users. The interface of arguably one of the world's best train systems is totally useless to people without the gift of sight. Only with the extra additions of these pathways does the train system become easily navigable by blind folks. What does your user interface expect people to have? Who does your interface exclude? New computer users? French speakers? Slow-typers? Android users?
Don't get me wrong, I'm not suggesting you should make your website compatible for blind-people, although I am sure there is a market there. I am suggesting that you restate your assumptions about your users and think about all the cases you might be inadvertently excluding. Next time you are designing a piece of your UI, close your eyes for a minute and try to use your application that way. I bet you can't and I bet you have users who feel the same way with their eyes open.
Yellow pathway along Tokyo Streets