Because by definition, criminals do not obey the law. If arms were taken out of circulation, there would be none to obtain except via smuggling --which is time consuming, requires connections, is costly, etc. It would certainly require advanced planning to carry out. The criminal could not just go down to Sears and buy one or down to the seedy area of town and then do a stick up later in the day.
That's why I'm putting it more like 20 years out. Eventually there will be printing technology that will provide the tolerances required for a complete gun that doesn't blow up in your face.
This is a very exciting future indeed. There hasn't been something like this since the home computing revolution. It's the 1970s again, and we're still at the Homebrew Computer Club stage.
Tell me about it. I went and bought a reprap. I now have a 3d printer on my desk that's priced well under a grand, that is cheap as hell to run and that is designed from the outset for making replacement and upgraded components for itself. - http://www.reprap.org
Why more people haven't bought one already is more of a mystery to me.
