I disagree.
It’s not about the design of our Constitution.
It’s about the execution of it.
History had shown that separation of power was the key, and a senate of the states was crucial. It wasn't until after the structure of the senate was determined in July 1787 that the states agreed to give up their powers in Article I Section 10, and grant the powers of Section 8 to the new government. Their presence in the senate was regarded a sufficient safeguard.
Ratification of the constitution itself was contingent on a senate of the states. It wouldn't have happened if congress was composed of two popularly derived bodies.
Our history, pre and post 17th Amendment bears witness, for the federal government largely stayed within its box before 1913. We wouldn't be staring at tyranny today without the 17th Amendment.
The president in modern times has way too much power. That needs to be addressed.