I've often thought that changing to a direct election of Senators fatally undermined the wise intentions of the Constitution's authors. They were very deliberate in structuring our nation's republic.
They did this because they had both the hindsight to avoid what the mess they came from and the foresight to see what America could be.
Unfortunately, where they were deliberate and wise, we in the 20th century have been politically hasty and foolish.
"Yes, we did produce a near-perfect republic. But will they keep it? Or will they, in the enjoyment of plenty, lose the memory of freedom? Material abundance without character is the path to destruction."
18th century American radical right-wing extremist, Thomas Jefferson