In most states, if you win the most votes, you get all the electoral votes for that state. That is what leads to swing states. If every state sent electors proportional to the vote tally, you wouldn’t have to worry about swing states.
Also, if you win a state 65-35 and you get all its electors, and another state by 51-49 and get all its electors… you really aren’t representing the will of the people very well. It’s been decades since a Republican president won the popular vote, but we‘ve had several Republican presidents during that time.