From my reading of contemporary documents (18th century documents) the idea behind the electoral college was to ensure that the smaller sates, most of New England, would have some voice in national politics. You could never tell, when starting a national campaign, when a few electoral votes would mean the difference between victory and defeat.
The democrats of the people's republic are very happy to reduce the importance of Massachusetts from minor to totally ineffective. But then, isn't this the same state that rewrote how they were going to replace Teddy Kennedy in the senate upon his death twice in less than a decade?
One additional advantage of the electoral system is that it gives an advantage to candidates who can summon moderate majorities in a large number of states, over candidates that summon huge majorities in a smaller number of states. The President needs to be President of the whole US, not just a few major cities.