well regulated seems to be the key
The unorganised militia is indeed the pool from which the material of the organised well regulated militia can be drawn. To expect "the whole body of the people, less certain officials" to be well regulated is confusing the organised with the unorganised.
Yes, the militia of 1789 no longer exists. But the same basic precursor does, the citizens of our nation. True, we would make a poor showing comparing skill and discipline against our forefathers, but the fact that is probably true doesn't invalidate the concept.
A group of individuals who don't know each other, and live scattered through out the city may not be a football team as such, but when they all show up on the field to play, then they are one. Not a good one, compared to professionals, but a team, none the less.
All else being equal (and it almost never is) bigger bullets tend to work better.