And when a car gets a flat tire, you don't get new car, you fix the flat. We can all come up with a useless analogy to make a empty point.
The fact is, the basic principles and concepts that were outlined in the founding documents - ALL men are created equal, and we are are ALL endowed by our creator with the inalienable rights to life liberty and the pursuit of happiness, et al, - are still relevant today, and are still the best principles and concepts upon which to base a government today.
We could fix a lot of our problems with a few easy steps, like getting all money out of political campaigns, but that would require all parties to negotiate with each other, AND the voters, in Good Faith, and that's what's been lacking in government. Very, very few of them, on either side, have earned the trust of the people, and many of them have earned unforgivable scorn. They need to start listening to the people.
So we may need to do some serious tuning up and upgrading, but the chassis and the body are still good, and the drivetrain can be brought up to speed, as long as the guys on the second shift don't keep coming in and taking a sledgehammer to it every night, and destroying all our work.