In response to Jurij Toplak's suggestion that the EC protects federalism: The American concept of federalism is that (1) powers should be divided between national and state governments and (2) the popular will should be balanced against equal representation of each state.
The equal standing of the House and Senate in legislative matters achieves the second goal. However, in some matters, like treaties and nomination of judges, power is shared between the President and the Senate. It is hence desirable that Presidential elections select whichever candidate best represents the popular will, to preserve the state/federal balance. We can debate which election method best ascertains the popular will, but the Electoral College is clearly a poor proxy for the popular will in any election that is either close or has 3 candidates.
