Isaac Asimov, in his masterpiece Foundation, imagined a distant future where humans colonized the Milky Way and established a millenary Galactic Empire. In this future, a genius scientist named Hari Seldon invented psychohistory, a new science that through the statistical analysis of the behavior of gigantic groups of people, could predict with mathematical certainty the future of humanity. Using this new science, Hari Seldon predicts the inevitable and imminent fall of the Empire, followed by a thousand years of choas, and convinces the Emperor to establish two Foundations in opposing corners of the gallaxy. The purpose of these Foundations was to compile all human knowledge in a huge Galactic Encyclopedia, with the goal of accelerating the reconstruction of civilization and the Empire after its fall.
Asimov's fiction is prophetic. Today, even the most optimistic wonder if human civilization can survive the rest of the century. So writing Wikipedia is also what Hari Seldon suggests: compiling all human knowledge to ease the rebuilding of civilization after its fall. Even the Foundations easily recall the Wikimedia Foundation.