These are excellent points. Whoever downvoted you probably stopped reading after point 1. Decentralization could help a lot. Switzerland, for example, has a very fine-grained system of political control, with only minimal power concentration in the capital. This increases political accountability as well as the costs of lobbyism. The reason why France needs such strong anti-lobbyism laws in the first place is because it has overly powerful politicians, which in turn attracts this kind of money. Dispersing power attacks the problem at its root cause.
I agree with both of you, although I'm not surprised you were downvoted. A few additional points:
1) Money has diminishing returns in elections. Once you have flooded the system with campaign ads, get-out-the-vote volunteers, analytics teams, etc, additional money eventually stops buying additional votes.
2) The wealthiest donors in our country donate the maximum to all candidates in an election. This is not buying an election, it's buying favors from whomever gets elected. There is a difference, and from what I understand of the type of campaign finance reform Mr. Lessig is advocating for, it fails to do anything to address this issue.
3) Democracy comes in all flavors, but IMHO the best is not the most democratic (gives the most people a voice), it's the one that distributes power most evenly across a population. I firmly agree it's the concentration of power, not the influence of money, that corrupts any system.
