The Electoral College was designed to protect States' Rights. There would be no UNITED States without it as the smaller States would have never signed on if it was obvious that the larger (more populated) States would make all the rules.
Same with having two Houses of Congress. For any law to pass it has to be approved by a majority of the populace (the House of Representatives, based on each State's population) AND a majority of the States (the Senate, with each State have an equal say on the matter).
Getting rid of the Electoral College will bring about civil war as the conservative "Red States" will not tolerate being governed by the liberal, socialistic "Blue States". California, Texas, NY, and Florida would control everything. (Actually the 10 most populated States have over 50% of the US population.)