These data are used for lots of stuff, including guaranteeing rights for protected classes, which in the US includes race.
For example, you could use this info to prove that a redistricting is racist and illegal by showing that it unfairly groups areas of certain ethnicities into one district. Without official census data that includes race, anti-discrimination legislation would be harder to enforce in the courts.
If you want to be sure to catch it next year, sub to the Canvas comm on toast.ooo!