Your defense of the 17 Amendment has faulty premises.
At present, a senator from a state can, and often is, funded by national (or international interests like Saudis, Soros, Iranians supporting Obama) rather than state interests and issues.
However, the central issue is whether we are going to allow Congress to do charity. Or, do we follow the Constitution and remember rep. Crockett’s famous “It’s not yours to give.” concept.
Washington had it right - “The Constitution is sacredly obligatory upon all.”
Remember, again, the central argument of the 17th repealers crowd is expecting some magical smorgasbord of statesmen to somehow find themselves elected. I suggest researching the membership from the Gilded Age up through the Progressive Era to get an idea of what led to the movement to enact the 17th. At least it ensures that every state has a shot at electing someone that represents our views. Absent it, close to half the states would be closed off for the forseeable future. The thought of my formerly corrupt legislature under Democrat bosses/thugs for nearly 140 years choosing puppets/hacks without interruption is a sickening notion.