From a reader:

Dear Jonah,
Good point on lobbying.
Is it worth point out that McCain-Feingold, combined with the 1974 regulations make lobbyists more important. When money has to be raised in small increments, it is important to please more donors, particularly those who might be able to deliver bundles of donations.
This logic actually might apply to public funding. One obvious objection to public funding of campaigns is that it means the government chooses who is and who is not a candidate worthy of support. The answer to that, some reformers claim, is to give each voter a voucher to pay for the candidate of their choice. In that case, the need to please various small constituencies would remain–probably increase.