The thing is that the leaders of the 1774-6 revolt were actually fairly conservative. They were basically the establishment in the colonies who were defending their privileges as George III's ministers looked for ways to cut costs and to tackle "the Old Corruption". That is how it was so easy to reach an agreement to end the revolt once it was clear that they couldn't stop the British armies from going where they wanted.
For example, an independent "United States" would have much less quick than the British turned out to be to abolish slavery. So you probably wouldn't have gotten anything like the Slaveholders' Revolt later.
