Beside that, the purpose of the amendment was to provide a clause that allowed a citizen to defend himself, and provided for the establishment of a "well-regulated militia".
The point is that a citizen should be allowed a weapon to defend himself in the appropriate situation. Obviously, this could not be limited to the weapons of the day, as attempting to defend ones home or family with a flint-lock musket would be extremely ineffective. Like Yecti said, the men knew better things were coming. They certainly never expected for technology to continue to advance, yet for the citizens to be running about with muzzle-loaders. In the context of the second amendment, as weapons technology advances, so does (or should) the privileges of a citizen.
Please note that I am not advocating or supporting extreme gun-nut propaganda. I don't really want every numb skull in the country having fully automatic weapons or powerful explosives; only that there be a balance struck that provides maximum safety for all citizens, which is what the framers of the constitution also wanted.
Having said that, I don't like the idea of Kirby having a gun. He's emotionally unstable.