while I agree with much of the sentiment, the legitimacy of this republic was intended to be democratic. the idea is correct, though, that the Founders, particularly Madison, felt that the threat of majority faction was greater than any benefit of responsiveness or accountability afforded by a more directly democratic legislature. representatives are, then, supposed to focus the interests of individuals into legislation that works for the public good, but the authority of the government is meant to come from the people (although only a small fraction of them in 1791).
further, the concern of the Founders was not to produce well-informed voters but to establish the institutions by which people could express their interests. by "extending the sphere" of participation, Madison thought that the plurality of diverse interests would allow all to be represented. freedom of the press was as much about defending basic liberty as it was about educating the public; the public education system had no place at the Convention or for many years after.
the systems which we acknowledge today as crucial to providing for individuals the tools to better exercise their will were mainly the efforts of the Jacksonian Democrats, the Progressives, the Civil Rights and other movements, but not of the Founders. it many ways, then, the means by which we have to influence the government have expanded greatly since ratification (this includes near universal suffrage).
the problem of why government seems so unresponsive today is by no means clear.
is it that the people elect representatives who deceive them and legislate in their own interest? is it that the people lack the proper political education to elect representative who will legislate for the public good? is the legislature institutionally constrained by their inability to enforce the law? are people simply so detached as to have no interest in governing? is government less responsive even than in the past?
you are certainly correct in one regard: we are ultimately responsible for how our republic governs--this is what makes it democratic.