Here's why we need the Electoral College: States Matter
The Founders of the country were smart. They asked several questions about how to protect people from each other.
One question was:
"What if a larger number of citizens - say, half - are concentrated in just a few areas in the country, and the other half are more spread out. If the concentrated half vote, their small region(s) could override the votes of much larger territories."
And that's what we had this election -- about half the population present in all 50 states, and the other half concentrated in large number in 11 or 12 states.
In fact, 1/2 of the votes for the Democrats came from one state -- California. The founders knew that the 50 territories would not be happy with one large state controlling the Executive Branch.
So the electoral votes cannot ever be concentrated in only a few regions -- the electoral votes are spread out. Even if 50% of Hillary Clinton's votes came from California -- and they actually did -- California does not have 50% of electoral votes. Once California is completely blue (more illegals and such), it's possible that 75% of the Democrats' presidential votes could come from California.
Now, there is no way that the 49 other states be okay with one state always determining the Executive Branch. And with the Electoral College, that cannot happen.
Electoral votes stop smaller areas of the USA from controlling the Executive branch.
Look at the map above and imagine that the few blue counties in the 2016 President voting outcome controlled the Executive Branch -- look at all the pissed off states that would result from that, the states with all the red counties.
Also, keep in mind that Donald Trump did not even campaign in California. If the winner of the popular vote won, he would have been there every day.