I personally believe that, in a perfect world, the law enforcement alone would be capable of wielding all the violence needed to keep society safe. However, this is an imperfect world. Criminals have gotten access to guns, and that is a genie that isn't going back into the bottle. The law enforcement has finite resources and can't always be there in time. Therefore I believe a person should have the right to arm themself for the purpose of self defence.
Further, I do not think that the actions of what is essentially the global bottom ten participants in a class of hobbies should be taken as a reason to limit said hobbies.
EDIT: Monday, Feb 20 12:45pm GMT (GMT+00:00); ClarRH.TV made a longish informative post on page 22, which you might want to check out; http://www.teamliquid.net/forum/viewpost.php?post_id=13598455
Another good one on page 23 by Nagano; http://www.teamliquid.net/forum/viewmessage.php?topic_id=313472¤tpage=23#441
Also, I keep runnig into demands for research findings such as these;
+ Show Spoiler +
Hemenway et al, "Firearm Prevalence and Social Capital" found that guns are more common in areas where there's low levels of social capital, that is people's trust in one another. Interestingly, they also used homicides and suicides with firearms as a measure of gun ownership.
Kennedy et al, "Social capital, income inequality, and firearm violent crime" found that "The profound effects of income inequality and social capital, when controlling for other factors such as poverty and firearm availability, on firearm violent crime indicate that policies that address these broader, macro-social forces warrant serious consideration."
If you feel this is a one-sided slice, PM me with a reference to research I omitted, and I'll put it up.