No state is in any position to try to leave the union at this point for a variety of reasons. If we rule that out, what utility does "keeping underpopulated states happy" provide, exactly?
The state system wasn't really intended to do anything, rather it was a byproduct of the fact that the founding fathers had to appease the colonies into wanting to unite as a larger entity without losing their local identity. It was merely a concession.
So electoral votes are largely a legacy feature from a bygone era where we had to worry about states trying to leave the union over minor grievances.
Combine that with the fact that cities and coastal states in general brain-drain rural areas, and you realize it's probably a dumb idea to give the brain-drained regions of the country the most decision-making power. The electoral college does just that -- it selectively gives vastly more voting power to the less intelligent regions of the country.
That said, it would also be wrong (both morally, and in the ill-advised sense) to have a meritocracy where high intelligence means your vote counts more. Since intelligence largely tracks with socioeconomic status because of access to different opportunities, this devolves to your classic rich noblemen making all the decisions situation with its obvious pitfalls.
So if you are trying to come up with an effective and fair system for electing a leader, sticking with the popular vote makes a lot more sense than affirmative action for places where no one wants to live.
The stupidity behind the electoral college is reflected at the local level in the stupidity of the system that allows for gerrymandering -- if there were rules in place forcing political districts to all be equal in terms of the % of the total population of the state that they represent, politicians couldn't manipulate the map for partisan purposes (at least as much as they do now).
As for the founding fathers' intentions, who can say? There was nothing really special about them anyway, they were more a product of their time than anything else. Now we are stuck with their mess.