From what I've observed, more people are leaving than new people are joining.
I think that opening registration again can help the playerbase reach an equilibrium. It'll help even out the people leaving to the people coming in.
I wasn't around when "The Hack" happened. But almost 3 years have passed since then and I think that the community has had enough time to heal. I know that the staff is doing what they can to prevent this kind of thing from happening again, but I believe that it's time to open the registration