If for no other reason, video is a much more ubiquitous format. And due to our social norm if an agency was to ask for video record for "some reasons" it would

If for no other reason, video is a much more ubiquitous format. And due to our social norm if an agency was to ask for video record for "some reasons" it would be far easier both technically and politically than asking Walmart to extract all customer data from date X to Y. Besides, your face is (for all practical purposes) all the data needed to identify exactly who you are, you name is just a few bit (albeit extremely discriminating one) of info and can have collisions. Being able to efficiently do thing that was possible but inefficient is a huge deal. Especially since the government was designed with inefficiency in mind as a check of power. Removing them means increasing their power, and absolute power corrupt absolutely.