Having the states responsible for running elections isn’t fair. Partisan state governments seem to think of all sorts of ways to prevent people from voting who are unlikely to vote the way the state government wants. So a poor black person (for example with a name resembling that of a convicted felon) might have a lesser chance of being able to vote in Florida than they would in another state. That’s not fair.
Having a 50.1% majority decide 100% of a state’s votes in the electoral college is not very representative.
Plurality voting is also problematic with more than one candidate.
The US is one of the world’s oldest democracies. If you’re first to get something, say an underground rail network, without a lot of upgrading work you’ll eventually have the world’s oldest and creakiest underground rail network. So I think the US democratic process could do with an overhaul, if only because other, newer, democracies have been able to develop their systems learning from older democracies’ problems.