Few internal links, means few visitors to a webpage. The amount of internal links for a webpage, tells something about how important it is. The more important, the more links. The more internal links a webpage has, the better it ranks, as internal links and the amount of them, dictates how much of the linkvalue for the website as a whole, has to be passed on to that particular webpage.
Webpages with few internal links, has a bad chance of ranking well in the search engine result pages. Especially webpages with zero or only 1 internal link, should be corrected and more internal links should be pointed to that webpage.