Some first rate thinking about these ethical issues can be found in a new article on the subject by Heidi Reamer Anderson called "Allocating Influence." I also like the historical frame that Anderson puts on the issue:
Influence peddlers, influence seekers, and government officials have a long and fascinating history. Centuries ago, those in need of government action greatly appreciated the value of 'an audience with the king' and paid handsomely for such access, to the benefit of both the influence peddler and the influence seeker. Twenty-first century influence peddlers offer influence seekers a similar service, but often do so subject to restrictions not faced by their medieval predecessors.
While we think of ourselves as a democracy and a republic, which we are because we rely on elections as ultimate arbiters of key decisions and lack a hereditary monarch, the government of the United States is just a shadow's breadth away from being a constitutional monarchy or oligarchy. Our federal judges serve for life (Judge Samuel Kent had been convicted of a felony, was serving his sentence, had been impeached in the House of Representatives and was facing an imminent impeachment trial in the U.S. Senate before his written resignation finally removed him from office this week), it isn't unheard of for U.S. Senators, members of the U.S. House of Representatives to spend multiple decades in office, and a large share of Presidents leverage their incumbency into a second four year term of office. Between biannual elections, those in power have an virtually uncontestable right to govern as they collectively see fit.
Elections, and the threat of elections do matter, those in power have had the grace to provide for public input, and the right to offer public input is constitutionally protected. But, our history as a modified monarchy explains a lot of American public law, the nature of judicial authority, and more.