I understand your position - though I find it morally vacuous. If individuals only have a right to defend themselves if the law states so, then it is no right. Your world view would deny all those resisting tyranny and oppression that same right, whereas mine says their rights to defend themselves are being violated.
The constitution did not magically create rights where before there were none, it merely recognized them. Anything else is window dressing on authoritarianism and statism.