Most of the people on the list haven't done a thing to even be watched. Making the list voluntary and only known to those who will be directly dealing with vampires and hunters gets rid of a lot of the inherent sense of suspicion that comes with it.
[Because Suzaku may have good intentions, but Rayflo wonders how naive he must be to think this kind of thing doesn't have negative uses if it's given to too many people. And who's to say that the Defense Force Headquarters is truly all that safe for that kind of information to be kept there?]