Sebastian Galiana and Gustavo Torrens have a new NBER paper on this underappreciated question:
Why did the most prosperous colonies in the British Empire mount a rebellion? Even more puzzling, why didn’t the British agree to have American representation in Parliament and quickly settle the dispute peacefully? At first glance, it would appear that a deal could have been reached to share the costs of the global public goods provided by the Empire in exchange for political power and representation for the colonies. (At least, this was the view of men of the time such as Lord Chapman, Thomas Pownall and Adam Smith.) We argue, however, that the incumbent government in Great Britain, controlled by the landed gentry, feared that allowing Americans to be represented in Parliament would undermine the position of the dominant coalition, strengthen the incipient democratic movement, and intensify social pressures for the reform of a political system based on land ownership. Since American elites could not credibly commit to refuse to form a coalition with the British opposition, the only realistic options were to maintain the original colonial status or fight a full-scale war of independence.
You may recall that Adam Smith wanted to see a continuing empire, but with North America as essentially the more powerful partner, though he did not quite use those words.