no you're right let's govern our 21st century country using the same rules as an 18th century agrarian country
You're implying that any part of the Constitution reflects the needs of a particular time, and not universal human truths based on Enlightenment philosophy. I think I would suggest the history class to you as well.
The Constitution has nothing to do with how our country is governed, it only forces us to make government as close to the people it serves as possible, and serve their interests as a whole without violating the rights of the minority.