Simple. Because the Second Amendment was an 18th-century version of nationalized health care.
Look, doctoring was shit in 1789. People had to have umpteen children, hoping half or a quarter of their brats might actually survive to adulthood. And, if you got a bacterial infection, in a world with no antibiotics—let's just say undertaker was very steady work.
So, death was part of the everyday experience and there wasn’t anything you could do about it. One thing people thought they could do about it was to hand out guns to intrepid pirates, and encourage them to go west into the vast continental frontier, far away from civilization, where the employment of firearms seemed a noble requirement—assuming the pirate wanted to stay alive long enough to steal stuff from the indians.
If nothing else, and this is a point often missed by the gun rights nuts, but guns gave people the comfort of knowing they could blow their brains out. How many gorgeous vistas of unsettled savage nature can you take (literally and figuratively), after all, without going out of your mind? How many savage New England winters? How many choruses of "Swing Low, Sweet Chariot" down on the dreadful plantation?
As Nietzsche said:
The thought of suicide is a great consolation: by means of it one gets successfully through many a bad night.
Second, and more satisfyingly, and more politically pertinent, guns gave people the comfort of knowing they could blow other people’s brains out. And, out west in the USA, that meant, among other targets, shooting indians, which the US government supported by repeatedly coming to the rescue of its informal invasion force of covered wagons and the intrepid pirate families they carried.
The comforting thoughts of suicide and the useful outlet of homicide got people through on many a dark and dreary night—along with the copious amounts of liquor everybody consumed. Adding guns to this barbaric mix of hopelessness, genocidal national policies, and drunkenness, just made sense to establish as a constitutional right for primitive Americans.
Additionally, of course, some of the Founders argued about the political utility of having an armed population. But since there is no evidence that having an armed population has ever mattered in the least, except to some extent in aiding a rebellion of pro-slavery traitors, the militia concern is answered by each state already having its portion of the National Guard.
The Founders could not imagine, and did not account for, a future where nations could employ single weapons that could vaporize cities. The people can have all the guns they want, but up against the most technologically sophisticated and destructive armed force the world has ever seen, their little Bushmasters and Glocks will be like firecrackers.
The usefulness of the Second Amendment, as a guardian of the political integrity of the nation, or as a means to secure the health and wellbeing of American citizens, seems therefore to have long ago run its relevant course. People can take drugs for their mental illnesses, and the USA successfully wiped out and/or locked up all the competing, indigenous populations a long time ago.
Eradicating the Second Amendment therefore seems a quite reasonable course of action. And, since more and more people need SOMA—really badly need it too—it makes sense to just go ahead and put government-supplied dispensers of feel-good drugs all over America.
Now, somebody—like a centrist jackass for example—might argue that we should provide for gun ownership licensing for those living in rural areas, where police protection is limited or nonexistent. After all, they might need to shoot some dangerous wildlife, or a noisy tourist family.
But, regarding that exception, maybe the time is coming, rapidly, to order human beings to stop demanding the right to occupy the habitats of all the other animals on the continent. Let’s restrict ourselves to a more vertical expansion, and then maybe the coyotes and the wolves won’t need to carry off our pets and small children.
And maybe we can stop pretending to ourselves that is always such a bad thing.