I'm sure this wasn't envisioned when the election of Senators by state legislatures was first conceived, but with the way district boundaries are drawn these days, the fact is that nowadays the HOUSE represents the state legislature (via gerrymandering), and the Senate represents the people of each state -- since state boundaries aren't redrawn after every census.
I remember one election when I lived in California (probably late 1980s) when about half the votes for Representatives went to each party, but about 2/3 of California's House delegation were Democrats. Why? The Democrats controlled the legislature -- and gerrymandered that, too, with similar results. At that time, California had a Republican Senator (Pete Wilson).
The pattern is probably similar in other states, though perhaps in some cases with the parties reversed. If the 17th Amendment were repealed today, it would not remove power from special interests, it would just ensure that ALL of Congress were chosen by gerrymandering, and it would make the political map at the time of the repeal more entrenched at the federal level.
His argument is flawed. State legislatures are elected for the sole purpose of running state governments. Therefore, senators sent by the legislature will reflect the state's interests.
Even though House districts are heavily gerrymandered, the people in them still vote for candidates based on their popular interests, not the interests of the state in which they live.
Do you really think a gerrymandered House district is going to be more concerned with states rights issues than a non-gerrymandered one?
Having said that, this amendment is going nowhere for the simple reason that people today believe democracy is superior to republic, and so would think that making Senators selected by state legislatures would be a loss of freedom.
You want evidence? Just look at all the ranting about how Bush won the election with less than the popular vote. People don't understand that Presidents are elected by the states, not the people.