EN, Your analysis of why the Electoral College was created is flawed.  The true threat to the various "small" states was large population centers (northern cities) dominating the new Federal Government.  Exactly what we would face today if the President was elected by the popular vote.   The "3/5" compromise came about to ensure the small and mostly slave holding states had a large enough population to counter that simple mathematical domination.  If this compromise hadn't occurred, there would be no Constitution and no Union.  The Constitutional debates began in 1787.  Slavery was still legal in some northern states when the debates began and those that had abolished slavery, had only recently done so.

So one has to ask themselves, what would have happened between now and then if the "3/5" compromise hadn't occurred?

Here's an easy to read simple overview of the Electoral College:  http://www.history.com/news/the-history-of-the-electoral-college-debate