[TeMPOraL]

Conversely, reading about such animals, my first thought is "can we please sequence their DNA already"?

That's one critical reason for being very upset about us extincting countless species, even those that do not play any significant role in keeping the planet habitable - losing all these genes means losing pages from a book that contains ready-made biotech, and information that helps to explain how things came to be (which helps explain why it works).