Let's just ignore all the Constitution, then. We can adopt Communism or Totalitarianism. Why not?
We adapt the Constitution to our modern society just as the founders intended.
For example, we now vote for senators directly. That was not the 'original intent'. But, an amendment changed the rules. That, of course, also affects interpretation of other aspects of the document.
The Civil War affected our interpretation quite a lot, by changing a number of the ground rules.
The point is that the Constitution is not a static document, nor is the interpretation of it static. It is *always* interpreted in the light of the current society and its needs.