"...get a constitutional convention by having non-corrupt state-level politicians pass an amendment."
Clearly you haven't been paying attention. State level races are as bad as national level when it comes to money as influence.
"So we're going to elect some politicians that promise to do something different? Where have I heard that before? (Every 2-6 years)"
Your gutless resignation isn't doing any good. Lessig has a great idea and he understands just how fundamentally broken the system is. He is fighting the system from within the system, something I didn't think was possible, but it's a really worthy goal. Be part of an attempted solution. Go donate. (And yes, I have. Twice.)