The Founding Fathers designed this system specifically because it wasn't democratic, though. Although the concept of today's Presidency is vastly different to how the Founding Fathers saw it, too.
Personally, I don't think there's a massive amount wrong with the Electoral College. Going full PR, one-person-one-vote, means that the campaigning will simply focus on urban and densely-populated areas, where it's more efficient to do so. Is it any better? Urbanisation may be the future, but a significant part of the United States is still rural, sometimes very rural.
PR empowers densely-populated areas, while the electoral college empowers divided states. Neither is necessarily right nor wrong.
Personally, I'd do something like the d'Hondt system (which is used in Scotland), something in between the two. You'd have a portion of votes being determined by the Electoral College, with a smaller portion of "top-up votes" based on country-wide popular vote. Maine and Nebraska do something like this - an alternative may be for more States to follow.
But even that is not as simple because this complicates the voting system. Complicated voting systems too have a cost - more distrust and confusion, for example.
You have to remember that the United States is constitutionally a union of independent States, who chose to sacrifice some of their sovereignty to a Federal government, in exchange for greater benefits by being a union. So a Federal solution may be a nightmare to do, and at a State level harder to achieve in deep Red or deep Blue states (why would California Democrats, for example, do this? It would simply grant votes to their opponents). Swing states may decide it's better, but then again, that means that Presidential candidates won't visit them as much, because they're no longer as important.