Thoughts go out to the injured, and I hope the POS is killed.
I hate to go so off topic, but you answer your own question in your post. You ask why we need guns, and the answer is in your last sentece, "hell, even the government misuses them." The reason why we cling to our guns so bitterly is because we didn't roll over and let our motherland give us our freedoms, we fought bitterly to a stalemate using those guns in the late 1700s. Not only were we told that our "right to bear arms shall not be infringed," the founders even wrote to eachother about the need for the citizens to have equal weaponry to that of an average infantryman to be able to overthrow a tyrannical government.
The thing people fail to understand about guns in the US is that there are too many of them for a ban to work. We have too much of a gun culture, which did not exist in places where strict gun control was "successful." Anywhere in the US where strict gun control is put in effect, like California, New York City, Chicago or Washington, crime takes off because only the criminals there have guns, compared to suburbs in the Midwest where at least half the houses have a gun, with little crime.
If there was an attempt to do as you said, removing all guns by force, that would launch a bitter civil war that would result in millions dead. Our military is having a tough time keeping a few thousand illiterate third worlders under control in Afghanistan, could you imagine the carnage that would come from 80 million gun owners with 270 million guns?