A significant portion of the US population is blind. These blind citizens often are able to lead independent lives which requires having the ability to "see" their money. Adding a Braille element to US currency would allow blind people to have the ability to transact monetary exchanges without having to include a trustworthy person (who would act on the blind person's behalf) as part of the transaction.
Yes, blindness should be a consideration in the design of American currency, because it is very easy to design currency to be able to be identified blind. Some countries use holes in the middle for certain currency. Other countries use raised bumps or ridges around the edge. This is a small thing we could do that would help a lot.
In my opinion, the current US dollar system does not take into account those who suffer from partial or complete blindness. A person who cannot see if unable to tell what denomination of currency he or she is even holding. I believe that there should be some sort of braille on the note to help these people. This just seems like the right thing to do.
The blind are unfortunately dependent upon other people or a seeing eye dog for help. It is a sad situation to find oneself in but changing the US currency for a certain group will start a chain reaction of small groups asking for change. This would be like changing the national anthem because the def can't appreciate it.