First and foremost, he will have been chosen by the constitutional rules currently in place. This alone is a source of legitimacy. Moreover, we simply do not and cannot know who would have won a national popular-vote contest had one been held. In such a case, both candidates would have run fundamentally different campaigns, emphasizing different issues and appearing frequently in states like California, New York, and Texas. Who can know how people in those states would have responded had they been as informed by exposure to the candidates and their ads as citizens in Wisconsin and Ohio? One cannot persuasively impeach the electoral vote with a national popular-vote number that was wholly irrelevant to the campaign that was actually run. The hypothetical question of who would have won a national popular-vote contest if one had been held is thus completely unanswerable. (One note: It seems odd to hear commentators from England, Canada, or other parliamentary countries criticize the electoral-vote system when, in their own countries, it sometimes happens that one party receives more total votes nationally for its parliamentary candidates, yet the other party with fewer total votes elects more members and thus chooses the nation’s prime minister.)
and: via a kind reader.