They added the militia part to make sure the individual states could maintain their own forces separate from the federal government. To make the militias work the people had to maintain the right to keep and bear arms.
They could have just said "The Right of the People to bear arms shall not be infringed". It would have covered militias too. They didn't
How would not mentioning militias cover militias?
I quoted a noted expert in language usage that says the militia clause does not limit the rights of people to keep and bear arms.
I see RW's point. The Constitution cedes certain, enumerated powers from the people to the Federal government. The Bill of Rights goes further and says certain powers the people are specifically withheld from government.
In the middle of that, they thought, crap, government needs guns. Let's make sure they can have them. What if government tries to get rid of it's guns, we can't allow that. So they put the right of government to have guns in the middle of the bill of rights.
Sly like a fox, don't you think? RW's a brainiac, he notices those things.