But...it wasn't. The colonies had been run by the Assemblies because of the vacuum left by the English Civil War. It was during the 7 Years' War that the British began to impose tighter control on the colonies, which the colonial elites were understandably annoyed about.
There were assemblies, and it was the post-7 years war attempt at imperial centralization that kicked off the grumblings for revolution, but why did they choose to be radical? The political program the elites went through, and backed by a decent chunk of the population were very much experimental and rooted in enlightenment idealism.
The colonial elite could have chosen to stick with a north American monarchy which was responsive to their interests, but they didn't. The went with an national scale version of their local governments, which for the time was yes, radical.
I don't think this was 'ignited' by the Revolution at all. In fact, the colonies winning independence from Britain probably delayed the abolition of slavery considering that Britain abolished it about three decades earlier than we did.
Indeed, according to
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Oh, it very much was. There was some small debate concerning the morality of slavery before the revolution, but the discussion did not become a national issue until the revolt. Many, especially in the north where slavery was weakest, noticed the discrepancy between the popular enlightenment discourse that invoked freedom and literally holding people in bondage. As I said, that debate even penetrated the south, something that would not have happened if it were not for the revolution.
British abolition was very much a result of the revolution too. Many within the British government, on the home islands and in the colonies (such as Lord Dunmore) used the threat of slave rebellion to quell revolutionary fervor in the south. When the revolution broke out, he stuck to his words and offered freedom for escaped slaves and a place in his army. The British (at least the army in America, the abolitionist movement in the isles notwithstanding) could care less about the slaves, it was just a means to an end.
This debate can also be seen extended, within poor white circles, to indentured servants and the apprenticeship system. After the revolution, the system sees a very quick death and is very much a result of the same national language of radicalism that permeated the revolution and led to abolitionism.
The "feared" Indian states? The colonials were more to be feared than the Indians, in my view.
From your Eurocentric 21st century seat, sure. Nothing can stop the strong white man.
Of course, historically, the Native Americans were in very destitute times. However, they were not helpless. The proclamation of 1763 was enforced for a reason. The British didn't really care to keep native American allies now that the French were out of the picture, but they did want to avoid an extremely costly and prolonged Indian war. And when fighting did happen, during and post-revolution, the American armies eventually triumphed but it was also extraordinarily costly. IIRC twice the entire continental army dispatched to destroy the Native Americans was destroyed.
The American government had no love of Indians, but they didn't believe they could just walk in and kill them all either. The civil war in the Iroqious confederacy very much destroyed one of the few Indian states that did cause pause for the American government.
The counter-revolution?
I wouldn't deny that the American Revolution brought about some very significant changes in the pattern of development for the (former) colonies. But I don't think it really amounted to much of a revolution because it represented the replacement of one imperial system with another, which was "radical" in some respects but in others (slavery being the elephant in the room) was hardly less conservative than Ancient Rome.
There is a distinct movement starting around the 1820s that saw to the reversal of many radicalisms from the revolution. Most notably in the participation of women in politics and public discourse. You see the female politician (a term for politically engaged women, not actual politicians as we use the term) fell to the wayside in favor or social issues, such as the temperance movement, or jail reform, etc. etc. The movement for female political engagement doesn't come back for another thirty years or so, around the 1850s. By 1820 the initial abolitionist movement also died a bit as slavery became very much entrenched in the south, it takes some time before it picks up steam again. There were other issues that appeared in the counter-revolution, but I can't remember them off the top of my head. It was the result of the radicalized revolutionary generation dying off and their more conservative offspring taking control of government.
And as I said before, what didn't get changed, such as disestablishmentarianism, the rise of the female politician, electoral democracy, the destruction of the apprentice system, and abolitionism in the north, was very much discussed publicly. You would not see the abolitionist movement take off if it were not for the revolution, as I said before. The revolution radicalized society, government, and most importantly, discourse in the colonies. It was a revolution through and through.
EDIT: If you want some solid reading, I can recommend a lot of books and academic papers that discuss the radicalism of the American revolution. I still have access to a lot of the academic readings I read for the class, as well as several books that discuss the roles of slaves and women in the American revolution.
Whoa! It was the Assad regime who began slaughtering civilians. The first people to shoot back were army troops who, sick of the slaughter, switched sides.
After the 17th century the Native Americans at no time posed an existential threat to the Europeans in North America, while the reverse obviously did not hold true, though the existential threat from the colonists was more of a long-term one. 
