Why is it "fundamental"? It's a choice, and clearly a very poor one.
Because the United States is exactly that, a union of fifty states. Each state gets representation in the federal government, each state has a say in who the president will be. Dump the EC and the low population states have no say in who's president. The same thing happens in the senate, each state gets two, doesn't matter what the population is.
It's how the republic was set up, and it's worked for near 250 years. That's a good system. It's produced what's arguably the most successful nation on the planet.
I know a lot of people want a more democratic system, I don't , I like the one we have. Democracy is based on the idea that a million stupid people will make better decisions than one stupid person, I've never seen any evidence of that.