By illegally restricting how civilians may arm themselves, Congress has kneecapped the intended capabilities of the militia. Standard military arms such as machine guns, armor-piercing ammunition, plastic explosives, grenades, RPGs, cannons and mortars, and recoil-less rifles are either taxed and/or require registration, or are reserved for law enforcement, or are banned from civilian use. This limits the ability of the militia to defend the homeland against foreign hostile forces and organized criminals. Instead, those capabilities and equipment are under the control of law enforcement and the standing armed forces.
It was argued that standing armies make the nation safer, since they can respond immediately. However, many of the founding fathers opposed having a regular army. The recent Revolutionary War had showed that the sovereign could use a standing army to tyrannize the people. Aside from that, standing armies require continuous funding, which increases the government’s appetite for taxes, another form of tyranny which the colonists had protested, “No taxation without representation.”
The need to pay the army leads to other forms of tyranny, because the government will want more taxes than the people are willing to give. That is partly what led to the lack of representation in Parliament, and why King George III imposed tax stamps upon the colonists and commanded them to give his solders room and board - it was to pay, feed and house his armies.
It appears to be no coincidence that WWI is when modern gun control was born. That is when America drastically grew its standing army.
It was also the heyday of regressive ideas such as communism, fascism, eugenics, and so on, which would require a disarmed people to implement. Imposing such policies would be impractical with an armed and free people.
And so the militia was disempowered.