Destroying this institution will mean the end of national campaigning (and the engagement, negotiation, and localized promises that go along with it). What politician will ever again stump in Kenosha or Breckenridge? What will a vote get you in Idaho or Montana?
If I can take issue with this specific point, we don’t have national campaigning now. Many states are ignored by both candidates, as they focus on the battleground states. Some of the biggest states of all, such as California, are ignored because we know the electoral votes for California will go for the Democrats.
And they should focus on the battleground states, because the goal is to get to 270 electoral votes, not to win some mythical national popular vote total.
2016 election outcome in King County: 149 votes for Trump, 5 votes for Hillary.
This problem, of ignoring states sure to go to one candidate or another could be fixed by states allocating their Electoral Votes by who wins each Congressional District, with the winner of the state overall getting the two extra EVs. Maine and Nebraska are the only two states that aren’t winner-take all.
The five or six smallest states would still be winner-take-all, but this would bring most states into play, but would never be adopted democrat-dominated state legislatures. Nothing in the Constitution requires ‘winner-take-all’.