Bear in mind that the framers of the Constitution were not all adverse to the potential for future bloody revolution, and in fact, wrote the Constitution to allow for and encourage that scenario. With that in mind, I could well see that the Constitution doesn't specifically prohibit the right of the individual to bear arms. I would also keep in mind that the idea of carrying a firearm was not so foreign in a time when most people still routinely hunted.
Does it hold true for today, that we should allow and indeed encourage our citizens to bear arms? I hesitate to endorse that if only because the young people of today by and large have shown themselves to be devoid of any notion of responsibility and consequences. Until we have managed to teach the "respawn" generation that they can't run around behaving however they want, it would be a Very Bad Thing to give them anything more lethal than a spork.