People have a supraceding right not to be harmed by the actions of others. Hence, we require people get training and a license to operate a motor vehicle. Or architects to get training, practice, and a license, so they don't build a structure that collapses and kills us.
Theoretically, I would say the same is true of gun registration. It is meant to keep guns in the hands of responsible people and out of the hands of irresponsibly people who than may do us harm. Whether it actually works as intended is a completely separate issue.
I tend to think that a lot more should be done regarding weapon ownership - comparable to the training, licensing, and recurring registration required for vehicle ownership.