"Here's one way to start: remove direct elections of senators. It makes lobbyists having to deal with 50 separate state legislatures rather than 100 individuals."

Lobbyists hear this and think "Oh boy! I get to deal with a set of elections that the average voter cares even less about than Congressional ones!"

Personally, I'd go the other way around, and switch to a Westminster system where you only have one vote for federal office, meaning that plans like Obama's small-donor system would be more feasible for the elections that really matter: legislative ones.