What is the point of a PhD thesis whose content already exists in published papers?
Like @ff524 (comment above), I too have found PhD theses useful, and over the years I've collected quite a few of them. I've actually purchased at least 20 since 1992 from UMI/ProQuest. Unfortunately, I don't have access to their digital archive, but I have also photocopied more than double this number from various libraries during this same period. I have often found  them to contain fuller explanations and motivation, more historical details, and numerous minor tangential results, all of which tend to get edited out in the typical concisely written published papers (I'm in mathematics).

To answer your question, perhaps what you can do is to write an overview of your results and how they fit into the larger scheme of similar results on your topic that others have done. Even if no one else reads this, it can help by giving a useful summary of your work that you can siphon off when you need to give talks about your work (such as in job interviews) or when you need to write introductions or abstracts for future papers based on the work. Also, if for some reason you find yourself not working on this topic for a few years and thereby forgetting some of the details, and you want to return to the topic, your summary and overview will be very helpful in remembering what it was all about.