We could use it to restore our own genome. The Y chromosome may become extinct in as little as 5Myr[1], such a record may allow our descendants to refresh it. We'd be avoiding a pretty common scifi trope (although the trope usually arises due to cloning).
Urban legend. Almost all of the gene loss happened 200 million years ago in early mammals. In the past 40 million years, our ancestors lost one Y-chromosome gene one single time about 20 million years ago. In the 7 million years since we separated from chimps, there have not been any genes lost from the Y.
Note: a similar shrinking pattern is seen in birds, where females have a small W chromosome and males have two large Z's.
[1]: https://www.nature.com/articles/s41598-020-58997-2