You seem to have the history of the Electoral College confused and completely backwards. It was adopted as an alternative to the idea of having the President be elected by vote of Congress. All sides opposed that. Key point: The idea of direct popular vote was not even seriously considered.
This was all related to debates about the composition of Congress. Virginia the largest state, was a Slave State. It wanted representation in proportion to population and including slaves in the total. The Free States were afraid of proportional representation for fear it would enshrine the power of slavery. The New Jersey and Connecticut plans were compromises in which states were granted more power, and slaves were counted as 3/5 a vote in awarding Congressional and hence Electoral college seats. The Free States were successful in offering compromises to limit representation based on popular vote. Not the other way around.