Not sure it's correct to claim that the big state/small state issue was dreamt up later. There's quite a bit (as in a lot) of contemporaneous writings, speeches, pamphlets, discussions, etc. about that issue and the compromises that were hammered out. You can agree which side had the better argument, but to say that it wasn't an issue (or even one of the critical issues) is intentional obtuseness.
The primary reason for the electoral college was to provide a check against the population's desires. In many states, this is now outlawed, as electors have to select the winner of a popular vote within the state. The issue of small vs. large states was more about the legislative branch. That is how we developed the Senate to protect small states. The Presidency was not meant to be another protection of small states. BTW, it isn't functioning as that either, as the electoral college means that about 100K low information voters in mostly medium to medium-large states decide the election rather than either large or small states.
Much to agree with in that post with some nits remaining to be picked. Thanks for a substantive reply.