That's a good point and I certainly agree the American Revolution was less a revolution and more an...exchange of hats, shall we say? The French and Russian revolutions represented much bigger changes of direction.
Arguably the American Civil War was more revolutionary than the revolution.
I took a class that more or less disproved this whole notion. The American Revolution was
very revolutionary. Not only in terms of government, where it was a giant experimentation with enlightenment idealism, but society as a whole too!
Just because the upper classes who revolted (due to a number of far more complex reasons besides just taxes, taxes were just an easy excuse/the straw that broke the camels back) ran the place afterwards does not mean a ton of radical change was not induced. Many in the upper classes (and the lower classes by extension) were actually fairly radical. Just read Thomas Paine's work, consider what he says, and then read all the people who argued against it. His advocacy for democracy and the destruction of monarchical institutions was the forefront of radical political thought.
In terms of social movements, there was also a ton of radicalism, and off the top of my head there was the disestablishmentarianism movement, which squeaked by with a surprising amount of support despite it never having been tried before. We have the igniting of the slavery debate, in both the north and the south. A surprising amount of debate was held, for example, in Virginia over the slavery question, even though emancipation radicals ended up losing out. It did however begin the slow process of emancipation in the north. We have women taking part in the political process in a massive way, something that
no one would have ever thought possible before the revolution. Although the only place they could vote was in New Jersey (if they had property), in all other states they joined parties and took part in the chaotic post-revolutionary partisanship.
Hell, we can push the radicalism beyond social and political movements as well. The revolution ignited civil war in Iroqious country, more else destroying one of the few feared Indian states in the North East. The proclamation of 1763, one of the major reasons for the revolution, fell apart and masses of people legally moved westward at a staggering pace. We also have a very large population of loyalists who exiled themselves, which included many (forget the exact numbers, don't have my sources on me) of slaves liberated by Lord Dunmore's army. Many of these people fled to Canada or further abroad; for example black loyalists actually founded a crown colony in Africa not even a decade after the revolution!
I'm rambling here, but the basics of my argument are that the American Revolution was actually fairly radical. People who like to tote around the "it wasn't a real revolution" are falling into the trap of not only failing to consider the context of the rebellion (this crap was very radical for its time) or having their history colored by the counter-revolution that occurred several decades after revolution.
Also the fact that all this change and radicalism didn't end with extreme violence, like in Russia or France. Just because the U.S. didn't collapse into civil war for another century doesn't mean that the changes brought about by the revolution were not radical.