Looking at the article, the basic problem is that if everyone is allowed to buy a gun without restrictions, I (an awfully big and very friendly guy) would not buy one, because I would never think I need one. A burglar however, would, since buying a gun legally is much easier then buying one illegally (you would have to find a retailer, for one), and then, I am facing a problem: When the gun laws where still in place, and there was a 'hot burglary', I could fight the burglar, or scare him off (I am bigger!). Now, he has a gun. When I attempt to fight him or scare him off, I might just get shot.
I might prevent this problem by buying a SPAS-12 shotgun, but that creates another problem: I just killed a (wo)man, and may have used to much force, making me a criminal and a murderer.