I think without a doubt any time you have a large database of potentially interesting information to anybody, it's going to pose a security challenge. I think that needs to be weighed, though, against the cost of having everybody repeat this exercise individually. Given the fact that you're now storing the same information, but in a whole bunch of different databases and that security issue still exists, I agree completely that you can mitigate some of those risk issues by controlling who gets access.
Personally, I'm not in favour of a completely public registry of any kind. I think there should be a stringent protocol around who gets access and for what reason.