American citizens do not directly elect the president. Moreover, the presidential election in not a national one. It is a state-by-state election in which American citizens elect representatives in each state. These electors then meet and cast their states electoral votes to select which candidate will serve as president.
The framers of the Constitution, who were politicians, were fearful that events of the moment, e.g. plagues, falsified votes, etc., and other factors that might sway people into rash, unwise decisions.
The Electoral College members meet together to evaluate all facts and then choose which candidate will best serve the needs of the U.S.A. After the Electoral College announces their choice, then — and only then — is there a president-elect.
The Electoral College is enshrined in the Constitution because of its importance.