The executive was purposefully designed to be unencumbered by deliberative process and act decisively, a protomonarch. Any modern concept of 'ethics' is the same concept of a leader's competency and demeanor. They didn't take quite the same moralizing lens to governance, debating the potential for despotism, zealotry or corruption. And recognizing that this was tied to partisanship and the regulatory ability of even this well intended safety valve of impeachment was subject to just being a process for a majority to strike down an opposition president. Any other alternatives, removing veto, oversight from other branches, whatever, it all amounts to nullifying the reason the president exists in the first place as a coequal branch of government. To act unilaterally, to be elected on the merits of his personal leadership.
that's a really good overview of 18th century intentions. but saying the executive branch is a "coequal" branch of government in the modern America is absurd.
even if we set aside purview over completely post-constitutional intel agencies, which is a big ask, the entire concept of equal branch governance was predicated on the system of ruling law in the country. drafted by congress or senate, ratified by the other house, and signed into law or vetoed. then left alone or struck down by SCOTUS.
most law in america is a perverted mixture of antiquated case law, executive branch non-congressional directives, and bloated regulations. we still have a solid backbone of criminal law codes, but federal criminal court cases are a vast minority. most of what we call "law" that is actually applied on a daily basis is just unchecked presidential whims while congress maybe churns out a porkbelly bill once a presidency and spends the rest of their time procrastinating the budget and interviewing intel members.