The entire principle of popular sovereignty, as exercised through representative democracy, is that leaders are selected according to the wishes of the the majority of the people. Minority rule--no matter how it is codified or how long it has been in effect--is incompatible with this principle.

America can be either a country ruled by a Republican party answerable accountable only to rural interests or it can be a democracy. It cannot be both.

That's clearly not the case as many systems (not just the US) seek to avoid "tyranny of the majority" and to protect the interests of minorities. Canada's senate does not use proportional representation either - that avoids the country being run by Ontario and Quebec at the expense of the other 8 provinces and 3 territories.

The designs you argue against were specifically implemented to provide a system of checks and balances to avoid a simply majority from unchecked rule. And this is doubly true in the US, where it's a "union of states", not just one massive country. A lot of those rules were put into place in order to get the states to join the US because otherwise they would have had zero say in the affairs of the country.

Those checks you want to remove are not a bug but a feature.