BlueTrain, good stuff.
Even though there were comprimises that had to be made to ratify the Constitution it was revolutionary. It is often said that "it's a document of it's time," "They couldn't forsee the future," etc, in reality it's true, but functionally they really are not true statements. It was believed when the Constitution was being debated and written, that they were really writing a "living document." "Living document" meaning it was based in principle and that it wasn't a "contract," outlining rights and responsibilities while dividing advantages between different groups or individuals. The radical concept was that right and wrong would always be right and wrong--yesterday, today and tomorrow. Regardless of the words, the principles of right and wrong would always stand the test of time. How do we live with each other beyond the god given inalienable rights.
The failure of the Constitution is also it's strength. Different people have different opinions of what right and wrong are. At one time people debated the virtues and evils of slavery, as already mentioned, just as today people debate the virtues and evils of guns. Unlike other documents like the Magna Carta, the Constitution does not tell us what the 2nd amendment means. We get to tell ourselves what it means. You're absolutely right that the people who debated, wrote and signed the constitution were radicals and progressives. They were not conservative. They believed it was a fluid document, but they also believed that if the day came that we decided that it is firm and hard as many today believe it to be, we have the right to that also.
That's the point of my earlier post and why knowing the context of the document is so important. The principles behind the document are way more important then the words. The context is in the principles. When you debate the principles, there is faith in each other. When you argue the words, you lose the faith in each other. Madison or Adams, I think?
Takes me back to my Master's Thesis on Economics, Environmental Regulations and Constitutional Authority. The Authority part put me in the middle of a circular firing squad of advisors. None of them agreed.