It is impossible to devise a political structure that works without an intelligent, engaged citizenry and patriotic, moral and dedicated leaders.
You want a parliamentary system? Take a look at the post WWII history of Italy.
There are several factors that have produced the current state of the US. Since the 1960s the left has been attacking the moral legitimacy of the US. In their minds, no matter what happens in the world it is the fault of the US. Some African country degenerates into permanent tribal warfare? America’s fault. (See the TP headline above the Sudan famine story.)
Meanwhile, the elites are downplaying the concept of America as a nation. They regard it as part of an international community, part of various trade blocks. American citizens and illegal immigrants are, to them, pretty much the same thing. America is just an umbrella for a “diverse” group of people with little in common except as consumers of corporate products.
Then, throw in the class division which, to some extent, follows racial/ethnic lines. You have a class of people who are dissatisfied with the allocation of resources in the country and want the government to pay for things they can’t afford — childcare, college, etc. And then you have the class of people who think the allocation of resources is just fine, and certainly don’t want to pay higher taxes to reallocate the wealth.
Each of these classes has its very own political party.
With neither of these factions believing in America as a nation and Americans as a people with its own customs, culture, civic faith and ideals, and with the population becoming progressively more ignorant of basic civics, elections become marketing campaigns. To the extent that they aren’t decided a priori by party loyalty, they are decided by the “independent voters,” who tend to be the least informed of all.
No matter how you structure the government, you aren’t going to get an optimal result.