Well if you don’t think it’s a big deal, you may collect it just to have the data (data was as appealing to bureaucrats 200 years ago as it is to big-data engineers today). For example the DMV asks for your height and weight today, but if a fat-hating government came to power and decided to kill all fat people, they would have a target list that was of very questionable value for the DMV to collect in the first place.