In 1929, G. K. Chesterton imagined a fence blocking a road: "The more modern type of reformer goes gaily up to it and says, 'I don't see the use of this; let us clear it away.' To which the more intelligent type of reformer will do well to answer: 'If you don't see the use of it, I certainly won't let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it.'"
Shorter version: "If you don't get why something exists, leave it alone." The election of Donald J. Trump provoked gales of outrage against the Electoral College; his inauguration and the run up to 2020 will likely increase the din. The electorally bereaved would do well to view their proposals through the prism of Chesterton's Fence: For the nation's founders, the Electoral College was a glue to hold the states together like a shattered teacup. Eliminate the institution, and states will discover the gaps that still separate the shards.
As a Virginian, the Electoral College means I don't have to trust the honesty of Illinois' electoral authorities or competence of California's. In the Jim Crow years of my Virginia childhood, Ohio and Massachusetts had no reason to expect fairness or decency from my state or, say, Mississippi; the Electoral College insulated states outside the South from my region's vile practices.
State authorities determine who can vote, who can't and who is penalized for electoral malfeasance; there's no feasible way to change that. Federal authorities have some influence (through civil rights laws, for example), but blunt federal instruments can only superficially prevent states from ballot-box stuffing or voter suppression.