The 2nd Amendment was created when the American military was in it's infancy and did not have the money to fund a large army. This was also pretty much after the USA had gotten independence from the British empire. Due to a small army, and law enforcement being anything up to a days ride away, it was important to arm the population so a citizens militia could be relied upon in the event of a threat to national security.
Today is the 21st century and a lot has changed in over 200 years. Those that think that guns are needed to defend against a rogue american government are survivalist nuts that think Obama is the second coming of Hitler and have no idea how a hand gun is no match for a Reaper Drone, Viral Bomb or a Naval ship blasting the shit out of you, two miles from the coastline.
An argument could still be made that for home defence, guns have stopped a burglar or home invasion.
Here is a table I came across:
http://www.allcountries.org/uscensus/333_murder_victims_circumstances_and_weapons_used.html
Note the percentage of deaths where guns were involved, compared to those of blunt objects, bombs, hand to hand, etc.
People forget, it's afar easier to shoot someone when its all over in one pull of a trigger. Looking someone in the eye and continually bludgeoning them to death with a rock or hatchet is an entirely different matter.
Unfortunately, guns are far to enshrined in American culture now. There are nearly 300 million guns in circulation....that's almost one for every citizen that exists.
By tightening up gun laws, you simply drive illegal guns underground. Unless the 2nd Amendment is completely scrapped, which will never happen, then I see the only alternative is to turn schools into mini fortresses. You dont see maniacs going postal in banks, prisons or military compounds. But then what? If schools become "gun nut proof", what then? Movie theatres? Supermarkets? Open parks? Theme parks? Where does it end?