The founders … wanted Presidents to be appointed by Congress.

So, like a… prime congressman? All the ministers congressmen vote in a Prime Minister Congressman to form the executive?

I agree with them entirely. The US is currently paralysed by a system where you need both a president and congress to agree before you can do anything, so if you have one opposed to the other then the entire government is basically useless and unable to reform anything until the president/balance of congress changes.

A parliamentary system avoids that problem by design - if the PM can’t get enough votes from the parliament, then he doesn’t have enough to “form a government” (I.e. become PM) in the first place. And if he ever loses majority support in parliament and thus can’t pass any bills, then parliament can kick him out via a No Confidence vote with simple majority support, so that someone who does have majority support (or gains it via negotiating support from independents/minor parties) can become PM themselves and the government is able to function.

Switching to a parliamentary system would be the quickest and easiest method of preventing another situation like Obama’s uselessness for most of his presidency because of a Republican-controlled senate.