Those were both from the 19th century when voters didn't have the kind of access to the candidates and the candidates views that they have in the 21st century.
Not to mention being another compromise between the 'every state should have an equal say in electing the next president' premise, which gives voters in low-population states a disproportionate amount of power in selecting a president, and the 'each voter should have an equal say in electing the next president' premise, which gives high-population states a disproportionate amount of power in selecting a president. The same compromise that resulted in the different representation between the Senate and the House.
And as you say, Trump played the game better than Hillary did; he approached the state elections as business transactions, putting his effort into the places where he would get the best payoff for his money. And it worked for him. Hillary got a huge margin of victory in California, which didn't help her any more than winning by 50 votes would have, and she ignored or only half-heartedly campaigned in states that she thought she had locks on... and was wrong in too many of them.