FWIW, I found census data extremely helpful when doing family geneaology work. The details don't become available for 70 years after the census is taken, and while the ones I researched didn't have income info, information about names, ages, race, occupation etc. helped me find my great-grandfather and his family, and his father's family, when none of my living relatives would have had any idea.
On the subject of race; I'm not always keen on filling it out, but I have fun when I do. Had to designate race on a form one time for a medical test; the condition is more prevalent in some races than others. When I got to the section where I had to provide this information, I thought... thought some more...... then asked the lab tech, quite honestly:
"how many can I check?"
She said; "choose whatever is most comfortable".
My response: "how far back do you want to go?" (that family history gets complicated...)
She didn't quite know how to respond to that one...... of the six they had listed, I checked two, and wrote in a third one on the freetext line (yeah, they missed one).
Left it up to them to decide how they wanted to classify; they asked the question