No guns=black market (like drugs)=people can still get guns (still lots of murder).
Black market=more violence (like the drug war and gang related killings).
So if people would be able to get guns anyways, why should we put up with exponentially more violence and an even larger increase to the amount of people incarcerated that would come from stricter regulations? If there is a ban on guns there is no way to control them at all since there would be no such thing as a gun registry.
The only way to get rid of guns is to wipe them from the earth as there will always be people to import/make them. However, this is impossible without wiping the knowledge of guns from our mind (men in black style).
What we need is less media coverage so people arent trying to die famously, more effective education, and better media. It probably is not a coincidence how much violent videogames, movies, and music comes out of the US, which also suffers from these terrible killing sprees. We import toys from China, and we export/produce violence.