From Michael Kinsley:
Declaring who won an election on the basis of who got the most votes would seem to be a pretty good way of going about things. But if you can bring yourself to admit that an absolutely precise vote is impossible, the value of the electoral college becomes clear: it turns close elections into solid majorities. It is no more accurate than a coin flip, but it’s no less accurate either. A coin flip is exactly what you need in an election where the room for error is larger than the winner’s margin (or, like this year, when the winner’s margin is actually negative: the loser, Hillary Clinton, got nearly three million more votes than Trump did).
The Electoral College is an artificial device, but it has the fairy dust of history sprinkled on it. It works so well that the nation soon forgets that a majority of voters did not want George W. Bush as president and do not want Donald Trump either.