I think if they knew how screwed up this was going to get they would not have adopted the Constitution
They only adopted the Constitution with the promise of the passage of the 12 Ammendments by congress. It took a few years, but they did pass and were given to the States for Ratification.
The Constitution is not the reason that things are screwed up today. The cause is the actual extra-constitutional activities by our government and the acceptance of such things by the citizenry.