To play the devil's advocate here, since there are already laws against assault and homicide, would you say that there should be no regulation of weapons?
And before you argue that weapons have no purpose except to break other laws, like jailbreaking there are many lawful or sporting uses of swords, firearms, explosives, etc.
We have laws against murder/assault, and we also have laws against making threats and reckless endangerment which I think should cover the other cases of bad things done with guns.
I'll go further and say that DUI laws are also redundant. Of course we don't want people driving drunk, but all we really need is some case law that establishes drunk driving as endangerment.
And before you argue that weapons have no purpose except to break other laws, like jailbreaking there are many lawful or sporting uses of swords, firearms, explosives, etc.