I simply believe that the framework of our Constitution has been far more successful than others, and especially the parliamentary systems you appear so fond of. They are close kin, but I think a system of regularized period elections is more effective than one where the government can be toppled on a whim of the electorate.
I may be misunderstanding you, but you seem to have some strange notions about parliamentary systems.
I know of no parliamentary system that can "be toppled on a whim of the electorate." All parliamentary systems are indirect democracies --- just as is the system of government of the USA. Governments can only fall by a majority vote of the representatives in the legislature, or by the resignation of the government, which usually leads to a general election.
The conservative part of me strongly supports indirect democracy. Just as much as the John Birchers and the Founding Fathers of the US Constitution, I distrust the "mob" and its fickle, empty-headedness.
In this respect I agree with the instigators of the American Rebellion, though I like to point out the Founding Fathers' anti-democratic statements, in order to provide a much-needed antidote to the semi-religious veneration which so many Americans feel toward that pack of scoundrels and traitors.
P.S. I am not so sure that the direct election of Senators, nor the holding of referenda, as they presently are conducted, constitute an improvement in the American system of government.