In 1974, Charles Press argued in 68 American Political Science Review 1756-58 that choosing the president by total national popular vote would "encourage a further nationalizing of American politics."  What he meant was that big city bosses and state leaders would lose influence over the nomination, and "Under [this] reform, you will be able to recruit your presidential candidates from South Dakota and Arizona without apology."  

Presumably he meant that each of the two parties owed the country a big "sorry" for the Goldwater and McGovern nominations but that a national vote might lead to candidates being chosen from small states.

Looking back at his point these many years later, it seems that "nationalizing" actually means that nominees would be less likely to come from a big state where they have a robust financial donor base. That seems good.