The electoral college must stay. Simple tyranny of the majority is never good. Government is already a blunt instrument as it is. Tbe choosers of leaders have no understanding of how to rule beyond their locale(if at that), and thus should not have unbridled power over areas where they have no experience with.
Many states are already monopolized by one party or another. It is extremely dangerous if the entire country falls into a political trifecta. It's kind of okay for an individual state to fall into such a state because the scope of control is limited to only that state, but unbridled and complacency, and corruption is usually not too far behind.
For the U.S simple majority rule pretty much just means being dominated by the most powerful state in the nation, which would be California.
The EC completely devalues an individual's vote based on where they live, and disenfranchises the voters who lose the popular vote.
Arguably the only people whose votes matter are those who live in swing states.
If you vote for Trump in CA, your vote counts 0 towards his reelection and does not matter.
If you vote Biden in mississippi, your vote counts 0 towards his election and does not matter.
That is patently absurd. Your vote should matter regardless of where you live. The EC makes it so it doesn't, and when it does, that your vote is more or less impactful depending on the state