A legitimate question to be addressed
Why doesn’t the 2ND Amendment just state
“The Right To Keep And Bear Arms Shall Not Be Infringed “
Why was the Militia phrase inserted
There are already those who claim that the Founders could not possibly have intended the "insurrectionist" meaning of the Second Amendment; that is, that the right to keep and bear arms represents the people's ultimate power to alter or abolish their government, a right of the people which was exercised by adopting the Declaration of Independence.
Without the Militia clause, they would be claiming, despite any Supreme Court decision establishing a protected individual right, that such right could not possibly include having any weapons equivalent to what the standing army or the police use. They would actually be claiming that our hunting or sport should be limited to muzzle loading rifles. You can bet on it.
My guess is that they didn't want a large standing army which they saw as a threat to liberty, so they stated an explicit benefit to the states of an individual right to keep and bear arms.
The militia clause was added to clarify the benefits of the right. RKBA isn’t just for individuals acting purely individually, it benefits the state & nation by creating a body of prepared & competent people from which a well-regulated militia can be drawn from on short notice.
Put another way...
Governments tend to suppress personal arms ownership; the militia clause explains that it’s GOOD for a government to have an armed populace.