The chief job of leaders in the Senate is to do the people’s business. The minute people in an organization begin protecting their interests and rights instead of doing what the organization is supposed to do is the minute the organization becomes dysfunctional. Unfortunately, that describes most of the government today.
I pick on this mainly because I suspect this sentiment is extremely widespread. It is, however, wrong.
To the letter-writer, I would say: go back to Madison, and read Federalist 51. For Madison, the self-interest of politicians was a given. What's needed, he says, is a way to harness that self-interest for democratic purposes.
Which is exactly what's happening here. Party leaders in the Senate look out for individual Senators' interests -- which means that they make it possible for Senators to work for their own states' interests.
More broadly, the entire US political system (and, I think, every representative democracy) is based in very large part on the career ambitions of politicians, and thus on electoral incentives. What's unusual about the US system is that great efforts are made to restrain the maximum influence of any one politician or even set of politicians (federalism, separated institutions sharing powers); and, at the same time, individually empowered politicians are given very different constituencies, thus giving them incentives to see particular, localized interests as well as or even more than the "national" interest.
Indeed, one of the big changes over the last fifty years or so has been the rise of the national political parties, which has balanced out to some extent the constitutionally-mandated bias towards localism and particularism. Whether that's a good thing or a bad thing is certainly a question for reasonable disagreement, but that it's happened is, in my view at least, clear historic fact.
If one believes that "the people's business" is self-evident, and that the majority will agree, then it's natural to conclude that something must be wrong with democracy when those self-evident policies are not being followed. The problem with exhorting politicians to just "do the people's business" is that what constitutes "the people's business" is contested. And what to do when large groups disagree about what is self-evident, or at least what is best, is the whole point of democratic design -- and a difficult problem indeed to solve.
Which is not to say that the Framer's solution, as adapted and modified over the years, is the only solution, or even necessarily the best one. But one doesn't get far in designing a democracy without understanding that basic problem.