Disagree. At the time, there was also no police force. I know exactly what a militia is, and how it is defined by the Militia Acts of 1792 and 1903. However, at the time, the US also also had no standing army, and nobody at the time could have predicted that our current military would have 500,000+ members, the most technologically advanced military in the world, and a nuclear arsenal. The intent, as you say, was for the defense of the country against an agressor, such as Great Britain. There is no way the intent of the second amendment was for your neighbor to own and openly carry whatever firearm he wants. You might read it that way, but I will disagree until the cows come home.
One of the intents of the second amendment was to raise an army against an aggressor, but also to protect our own government from being tyrannical. You're right, the founders never intended for us to keep a large standing army, and would probably disagree with us keeping one now. A big reason why is they wanted us to stay out of the affairs of Europe, because they knew it would pull us into war.
You're willing to bring up what the framers were intending when it fits your argument, but totally ignore their opinions when it doesn't. The framers did want Americans to have the right to bear arms. The framers themselves carried concealed firearms. The framers feared a government that disarmed its populace. The framers were more than ok with anyone owning 20 guns, because many of them owned many guns.
I provided a link earlier in the thread with direct quotes from the framers on why they felt the 2nd amendment was important. I provided another link that interpreted the linguistics of the time. Feel free to read them and do a lot more research on why their direct quotes matter when they support your argument, are useless when they don't support your argument.
You're just seeing what you want to see. The 2nd amendment isn't personally important to you, just like how some ppl choose not to vote and others are ok with Uncle Sam snooping around their/your email. So if it just goes away, or other laws are created that make gun ownership all but impossible and/or too expensive, as many states/cites have done, you're ok with it. After all, it doesn't really affect you personally and you think the amendment is outdated or needs to be "reinterpreted" for modern times. In short, no matter what opinions the framers had when drafting the amendment, you feel it's outdated.
The problem that I have with your opinions on guns and gun ownership is that you really do feel you're "letting" me have a right, or at least enough of it that I shouldn't complain. If I have just one musket, it's a gun, right? You're not "for" complete criminalization of gun ownership, but you're ok with many obstacles to gun ownership, or at least turn a blind eye to the many states and cities that have created those obstacles (Chicago, DC, NJ, CA, etc.). You're aghast at the willingness of red states to create laws you feel are unconstitutional towards the LGBT community, yet you, and many on the left, ignore the 2nd amendment for what it is and what it was meant to be. It's easy because you don't like guns, and you especially don't like the people who like guns (very fair statement based on how you describe gun owners).
Yes, the NRA goes to far sometimes, even in my opinion. But so does the ACLU.
If you want to rewrite the Constitution, there are clear ways of doing that. Your willingness to "reinterpret" the Constitution, or just ignore the parts you don't like, will come back and bite you and every other person in this country some day.