See D. Stephen Heersink's comment he left on my last post which deals with republican institutions in our liberal democracy, the United States.
Interesting observations as usual. The country is wrestling with many of these ideas, and obviously not coming to the same conclusions.
Yes, the U.S. is a democratic republic for precisely the reasons given. Plato in his Republic identifies democracy as the second-worst form of government after tyrany for the reason of mob rule.
But our republican institutions were finalized by the democratic process. The Constitution, after all, had to be ratified by the States. Whether the ratification came by plebicite or by legislative approval, clearly each State had to approve the final document that established the republican form of governance.
Only a lawyer would see the three levels of government as hierarchical. I suggest that they be viewed synergistically. Each has a "veto" over the other. For example, the Congress can impeach the Justices, so who really has the final word?
You cite Kelo, certainly the most incredulously decided case before the Court. The reason it took so many by surprise is that the Court did not take the Constitution as final or the Justices as final arbiters. In fact, Stevens made the point that he thought the legislature(s) should have the final say, which is why he voted as he did. But the Constitution does not allow for legislatures to trump the Constitution, so how could that have been Stevens' reasoning? If the Court is the final arbiter of consitutionality, why in this case did it defer to the legislature(s)? The amendment does not give legislatures that power, and the Court defering to that institution "closest to the people" abdicated its responsibility to affirm what the words actually state. That's what makes Kelo so incredible!
Ultimately, the democratic motif must prevail, even if it is hand-tied by republican institutions to avoid mob rule. People already feel their vote does not matter, but if they felt they could not change things, they would resort to violence and revolution, rather than the ballot box. Now, no longer secure that the Constitution is the final say (i.e., Kelo), people are genuinely anxious that our system of balances is truly failing. Each of the Justices who voted for Kelo should at least have been impeached. Congress should have insisted that the Court, of all the branches of government, enforce what the Constitution clearly states. And the Constitution, not legislatures, are supposed to be the final say on eminent domain.
People have come to appreciate divided government for the same reasons the Founders appreciated the three branches. I strongly suspect the House to change parties at midterm elections, precisely because people are fed up with Republican rule. The people's instincts are clearly in the right place, as we are careening way off course under Republican rule.
Still, people's confidence in their form of governance could not be lower. The Referendum process, the most democratic of all our institutions, has been thwarted by the Courts more often than not. And the Courts' justifications are often without constitutional reasons. They are not arbitrating Constitutions, but arbitrating policy. Californians have just about had it, because so many referenda have been dismissed by its Courts. The Rose Bird Court may not be the only one to be ejected.
Californians can, and have, nullified justices; Congress can, but rarely, has impeached justices. When Courts can't arbitrate the obvious, and if the people did not have recourse, either through nullification or impeachment, the system would break. That either recourse is available speaks against your hierarchical claim, and that the people ultimately decide. We certainly have put up obstacles to mob rule, but the valves are there in case they are needed, so that the final arbiter is not the Court, but the people.