Citizens being armed keeps the government afraid of us. Without that, we would have even fewer rights left than we already do. I can tell you from personal experience that there are lots of country boys waiting for the government to try and take their guns.
If the government ever did try, it would be the Revolution all over again.
That's not what typically happens though. How many times in the last hundred years, have you seen a government, that didn't have at least minority support in the populace? At least in states that started out as democratic?
What you'll get in lieu of the revolution, would be more like a second secession. And then you'd have neighbors shooting at one another across makeshift barricades, while military and national guard forces take sides and add a full blown military conflict into the mix. If the military completely sides with one side, there will not be a war, but merely a slaughter.
And if you truly want to goose the government, it'd not with guns that you do it. A simple strike suffices. The French government is more scared of the unions, than it is of giving guns to everyone in the country.
More important than any personal gun ownership, is a military that is diverse, and in close relation with the public that it is supposed to protect. That is the idea of the militia, more than anything else. An army of the people, for the people. As long as your military will side with both sides of a conflict, at least there will be a balanced slaughter, instead of just the extermination of the trouble makers.
I think this fear of the government, that many in the US have, is on one side due to the strong bipartisanship, where there is no real alternative, and no escaping one of two ways of government. On the other side, the US is geographically large, and the federal government always appears to be a distant entity, that should have no say in most matters, as it's too far away.
People are far less worried about a state government going rogue.
As for relative violence ratings: I'm not sure you can really compare it, as most of Europe is settled much more densely than the US, which usually leads to more potential for violent crime. I wonder how immigration and organized crime figure into those statistics as well, as Europe is a more convenient immigration target, and immigration often does bring with it a number of social problems that can often end in violence.
And with regard to the militia issue: Why is it acceptable to stick to the 300 year old definition of militia (which apparently meant nothing beyond "some guy(s)"), but not the 300 year old definition of arm?
It's all a bit confusing. And I'm still not personally convinced, that in modern times a well regulated militia remains a requirement for a free state. But maybe, just as I use reasonable definitions for "militia", my definition of a "free state" is also "wrong".