I'm a software systems guy. That means that my job is to design (and frequently implement) thoughts into concrete form. I'll pull a Den Beste here and state that I'm exceptionally good at my job. A big part of that is understanding that no system built by humans is perfect and that one never has infinite time or resources. It only takes a mediocre systems guy to think of something wonderful. Actually building something that works and people will pay money for is something else. One of the most irritating things is to have to compare one's built and working system with some marketecture utopia that's better, faster and more full featured because it hasn't been worn down by the friction of reality.
So the greatest respect is reserved for those people who actually put working systems in the field. As in systems design, so in Constitutions. For a Constitution is really a functional specification for a government. It describes the different modules, what they do and how they should interact. And just like with systems it's easy to design some perfect utopian constitution as long as you don't let dreary reality intrude on your pristine design
The Founding Fathers didn't take the easy path, they didn't just theorize, they built and delivered a working government, one that has survived for centuries and delivered fantastic value. It's certainly done better than the new and improved version developed in France a few years later or the impossible to implement Marxian design. The Founding Fathers did it with a clean, elegant design as well. Sure, it has its problems and warts but it's there, as is said, “in the field”. A stunning achievement and one that shines with a greater glory every year.