In my work as Internet Consultant I often run into poorly linked content. Making useful links in your content is one of the easiest methods to improve your ranking in Google. And it helps the visually impaired get a better online experience.
One thing people do when visiting a page is quickly scan for linked content. It’s, next to reading the first sentence, a pretty good way to know if you’re on a possibly ‘right’ page or if there’s a link to something possibly more interesting. So making links in your content is a good habit. No need to link everything, just link to sites and pages of which you know they deliver good and relevant content. (Relevant to the subject of your page.)
Visually impaired people do the same except they don’t have a trustworthy set of eyes to do the job for them. They use a program to read the page aloud to them. Having no links in your content forces them to either just start reading or, more likely, dismiss your page as irrelevant. So make some links!