The electoral college is a check and balance against majority mayhem created by politicians only going to high population centers. Entire states or sections of the country would be seen as being unimportant.
The presence of the college forces candidates to campaign in areas that would otherwise be ignored.
Lets say the the entire east coast and west coast were entirely republican. If you captured those 2 areas the rest of the US almost becomes irrelevant.
That's exactly what you have now with the highly populated Northeast and West Coast. As long as they both lean the same way 2/3 of the countries votes will not matter.