My opinion:
There should be a balance of security to threat. While I think the second amendment bearing of arms is considered by most for personal/home threat use, the founders were more concerned with warding off tyranny. Tyranny is ALWAYS a threat in a non perfect [ read: OUR ] world and the best method of deterrence is an armed populace that prevents government from getting any errant insubordinate ideas about who is ultimately in charge here.
The more gun/weapon owners there are, the more credible the risk to those considering imposing the totalitarian threat upon the rest of us. There are basically what, 320 million of us, many with some form of weaponry and in sufficient numbers to offset the technological advantages, that we know of, in opposing a theoretical bad government with, currently, a relatively small military. Not precisely knowing who in the general population might be your opponent, what kind of weapony we possess along with the historically proven difficulty of overcoming guerrilla styled tactics advantages us, we the people.
So it becomes necessary for a sort of ongoing dynamic balance. The larger our government becomes, and the more technilogically able to subvert we the people, that peril always being present [ even though the left only feels this to be so when, say, a GWB with the R behind his/her name is in charge ], the more lethal the weaponry of the common populace should be.
A reduction, IMO, to about half the current size, scope and interference of our current Federal government involvement in the lives of common citizens...and what is legal now should be sufficient.