If we had a popular vote, Trump would've camped out in New York and California and made those votes up easily
If it were according to popular vote, the candidates would all concentrate on big urban centers (where the potential voter concentration is highest), and the rest of us would never see them. Nor would candidates care about the concerns of flyover country.
If we had a popular vote, more Republicans would likely turn out in places like California and New York if they thought their vote would really count. Many Republicans in solid blue states probably don’t bother to vote currently.