Internal links of a website is one of the most neglected aspects of SEO in many cases. Although inbound links do not carry same value as by external links, they are important to help search engines understand site architecture, internal flow of PR, indexing of more pages and leverage the use of anchor text within a website.
It also improves user experience and leads to more page views on the website. Websites such as Wikipedia are using hundreds of internal links to their own advantage. Also, search engines do not differentiate between internal absolute or relative links.