I could be wrong, but I thought part of the reasoning for the electoral college was to appease some of the smaller less populated states. Going to a straight popular vote I think would diminish the importance of votes in less populated states...
I'm no political expert, so take my words as just a frustrated citizen trying to be objective for new reasonable solutions.
The president was originally designed to be nothing but an executive of a federation of independent states. According to various constitutional theory, this is counter balanced by the popular vote derived congress.
The original idea was that the president would be elected expressly by congress with no actual citizen voter input. This was eventually morphed into the current electoral college because of a fear of the populace being distrustful of a president elected by a relatively small group of people who meet together on a regular basis.....IE corruption, and the divisive issue of suffrage rights and the slave population.
While you were correct, somewhat, in that smaller states supported the idea because of them viewing it as a way to maintain a fair shake in the process counter to their smaller population - it was not the primary reason for it's inception.