The reality of these lines are usually less noble than you describe in many cases.
As an example, if you read about the motivations of specific actors in the American revolutionary war, many of the top dissenters were basically interested in not paying taxes and being the boss of their own piece of land (instead of having oversight from across the pond). Nobody is ethically pure, of course, but the main push for the revolutionary war was done out of massive self-interest from people in power.
"There was a time that we were noble" is something that rarely plays out in practice. Why should it? If anything humanity has gotten more, not less, ethical and noble over time.
There's an idea of fighting for justice and truth, and then there's trying to die to establish lines on a map. They're not the same thing, and I'd say that it's rarely coinciding in practice