To our Founders, the right to bear arms was not merely a right useful for maintaining balance of power. More than that, regular carry was conducive to good character, absolutely essential to a nation of free men. This point is eloquently made in Eric Raymond's essay "Ethics from the Barrel of a Gun: What Bearing Weapons Teaches About the Good Life" – a quick and enjoyable read I first discovered when a student brought it to my first concealed carry class three years ago. Eric says his essay was inspired by a longer essay "A Nation of Cowards". I note also that the title of his essay appears to be spun off the famous Mao quote: "Politics grows from the barrel of a gun." On this I actually agree with Mao, but Eric goes further, making this important point: The regular bearing of arms preserves the dignity and character of a free people.
Also, take a look at my post on the Christian view of self-defense. That post links to a number of articles, including an excellent "must-read" by Dave Kopel. [Kopel cites Professor Volokh's use of the term "pacifist-aggressive" to describe those who wish to impose their pacifist beliefs on others. Interestingly, a few nights ago my wife (who like Volokh, is originally from Soviet Ukraine) used the same term to describe communists. We were watching a documentary on Muzzolini and she used the term to distinguish fascists, who emphasized use of violent militia groups, from the "pacifist-aggressive" communists who better hid the violence (mass starvation, KGB visiting at night).]
And here are my thoughts on how someone like Ayn Rand could fail to appreciate the right to bear arms.