The most basic definition of "government" is: "The entity within a given time or place that possesses a monopoly over the legitimate use of force." (In this instance "legitimate" is self-defined by said "government".) Look most anywhere else on earth, "those who have the guns, make the rules".
The United States of America, "Of the People, By the People, For the People", our beloved Constitutional Republic, DOES NOT EXIST, unless the average citizenry at least has the potential participate in "the legitimate use of force". If an outright ban on any arms of military utility comes to pass, this nation will still be called the "United States of America" on all the maps, but it will no longer be the "United States of America" that came into being on July 4th 1776.
The entire nature of our system of government is based on checks and balances, the wording of the Constitution itself, and all the Federalist papers bear this out well past the point of debate to any honest and open reading of them.
States rights Vs. Federal powers, strikes a balance between anarchy among states, and a overwhelming centralized national government.
Executive Vs. Judicial Vs. Legislative… I won't even bother, everyone here hopefully went to grade school.
The two Senators per state Vs. the proportional population of Representatives in Congress strikes a balance between all states being equal in the union, and giving proportional representation to the larger states..
The Electoral College for President Vs. Popular vote for Congress strikes a balance between "pure democracy" and "mob rule".
And the list goes on...
Everywhere you look, there are checks and balances against any one entity in the United States having too much power over another. The same is true between the citizenry at large and the government itself, and this was by design. That is why so-called "Assault Rifles" must be protected. The framers of the Constitution probably did have "crime" and "hunting" in mind when they added The Second Amendment to the Bill of Rights, although one might argue they felt those "needs" were so basic and obvious they didn't bear mentioning. Unfortunately, they likely had too much faith in their fellow man, and failed to imagine just how badly their words would be twisted in the future.
However, the one purpose for arms they did enumerate was telling, for both their foresight, and in their lack of faith in government, however well conceived. The Second Amendment was written as both a balance against the power of government, and as a last-ditch defense against overt tyranny. And without the threat of force to back them up, all other rights are ultimately meaningless words. The "militia" as then written, was simply, "anybody capable of fighting". There was no "National Guard", or "Reserves" at the time. And if these forces today are separate enough from Federal authority to satisfy the idea of "the militia" as written in the Bill of Rights to satisfy a "states rights" interpretation of the Second Amendment, why are they serving halfway around the world in Iraq right as you read this? How come no Democratic governor who opposes the war, or the Bush Administration could refuse to send them?
Whether you like it or not, you are free, at least in part, because some of us have those "awful assault weapons" in our closets and in our gun safes. To paraphrase a famous quote: "Those who would trade liberty for safety, will soon find they have neither." All the hand-wringing over gangs, drug dealers, and the occasional school shooting, pales in comparison to the threat of genocide, however remote it may seem. "It can't happen here" is the ultimate in famous last words. Ask an African American, someone of Japanese descent who happened to live on the West Coast during WWII, or a Native American sometime. Or, imagine you had a time machine, and could go back to 1925, find a Jewish intellectual sipping coffee at a street-side café in the most bohemian part of Berlin, and you told him he and most of his family would be ashes before 1945 was over. He'd probably run the risk of dying from laughter before it ever even happened. All food for thought to anyone with an open mind, who truly values their freedom.
When guns are outlawed, only outlaws will have guns. It's trite, but it's also true. After that, if your government turns outlaw? Sorry, you're screwed. The Founding Fathers cared enough to at least ensure we had a chance to prevent that from happening in the Second Amendment.
It's understandable that to think like this makes people nervous and uncomfortable, but like smoke detectors, seat belts, and life insurance, it's no less valid.