The reasons are many for the use of Census information.
The current Census population numbers in a pre-defined area determines the number of congressional representatives elected, for both State and Federal Congress. Note: Senators are limited to two from each state for the Federal Senate.
The completion of the 2020 Census (a 5-minute process) ensures the City of Wilburton qualifies for specific grants which has a population requirement. So, you are benefitting not only yourself, but your community, financially.
Past Census are often used for location of older families members, finding the lineage. If you have ever tried to develop a family tree, your information often comes from a past census.