Why would the Book of Genesis have an entire chapter of names of a non-Israelite dynasty, with no narratives attached? What is the purpose of this information? Why was it included?
My answer is that this chapter is part of the Bible's "junk DNA." Once upon a time, remembering how the descendants of Jacob (Israel) were related to their cousins, the descendants of Esau (Edom), would have been considered important. Lots of us remember the names of ancestors and relatives, often long-dead, of whom we know nothing else, simply because remembering whom you're related to is part of remembering who you are. In the case of the two nations who lived side by side for so long, this would be important on another whole level. The Israelites were related to many other nations in their locale (e.g., Moab), but had, on the whole, less hostile relations with Edom than with most of their other neighbors.
Anyway, it seems to me that the oldest parts of Genesis, existing long before the material was assembled into a book to serve as prelude to Exodus, would be the family chronicles of Abraham, Isaac, and Jacob. A lot of information about the cadet families of this line of descent (Ishmaelites, Ammonites, Moabites, Edomites) was remembered and held to be important. When it came time to assemble the whole Book, this old, dryasdust list of names just couldn't be left out. It was part of the record. It had been treasured, even if with ever-decreasing relevance, for so long.
Today, the Dukes of Edom stands as probably the least inspiring chapter in the entire Bible. But it gives a vital clue to how the Book of Genesis was constructed, and so deserves at least a once-in-a-career mention. Or at least, a blog post.