Web pages on your website have a page authority which are assigned by search engines and so even though they may seem like not generating a lot of traffic you should not ignore them and try to use them directly or indirectly on your website.
We recently updated a client website based on WordPress and implemented a new theme on it as well as added some new features on it. The client had been running this website for over 2 years and he was looking for a major website overhaul.
The client was maintaining the website for the past 2 years on the same sitemap and wanted everything new on a new theme.
After we completed the theme implementation on the new website the client then added the older pages of his current website to the new website. This was not an issue with respect to the website look and feel as he was in his right to add whatever content to his website he wants but the problem was that the old pages would not be able to take advantage of the importance (Page Authority) search engines had placed in those pages. The client had also not been using permalinks on his website where as we had implemented it with the new theme as that would help the website on search engines.
We compared the current website sitemap to the new one and found that there were over 20 pages which did not exist on the new website. The only logical thing we could do was write 301 redirect rules for those pages so they could redirect to the new urls.
Moral of the story: Every page on your website is important so never disregard your old pages. Search engines regard the age of the domain and its pages very highly and you should always use them whether they may seem useless to you.