I like this analogy (at the Huffington Post, of all places) explaining why, given the electoral college reality, it is both misleading and damaging to go on and on about the "popular vote."
The year is 1960, and the underdog Pittsburgh Pirates face off against the feared New York Yankees in the World Series. The Pirates take the first game in a squeaker, 6-4, before being blown out in the next two games, the Yankees winning 16-3 and 10-0 to take the lead. The Pirates aren't demoralized, though - they fight back, winning the next two games 3-2 and 5-2 on the strength of good pitching. But the Bronx Bombers strike again, demolishing the Pirates 12-0 to tie the series at three games each. The pivotal seventh game goes into the bottom of the ninth inning, when Pirate Bill Mazeroski hits a pitch over the left field wall to win the series for Pittsburgh by a score of 10-9.
But wait a minute. Did Pittsburgh really win? I mean, the game of baseball is all about scoring runs, isn't it? And if we add up the runs, it's clear the Yankees were better: they outscored Pittsburgh 55-27. Clearly the Yankees were really the winners - the Pirates' World Series victory was illegitimate!
Sounds ridiculous, doesn't it? After all, the goal of each team was to win four games, not get the most runs over the course of the series. Yet this is exactly what people do when they talk about "winning the popular vote". This measure is like adding up runs in a baseball series: it is tallying the votes of 51 separate contests, which is not equivalent to properly measuring popular vote across an entire nation.
He doesn't argue for or against the electoral college. He just points out that it's the system in place, so it governs what the candidates do -- the rules determine the goal, and the goal determines the strategy.