I've always hated the idea of public financing anyway. Why should I give any of my tax dollars to the campaign of a candidate whom I don't support?
Prior to 1972, there were no restrictions on contributions. Ironically, it was Nixon who signed the 1972 bill. Another followed in 1974, and then again in 1977. The checkboxes on IRS 1040 forms appeared in 1976.
As much as I didn't want Obama to win, I think it's fitting that McCain was defeated in large part because of a law he authored. It's ridiculous to think that the flow of money into politics can somehow be regulated. Plug one hole and the water flows through another. It's much better to have full disclosure so that we know that George Soros gave Obama $100 million than to have Soros move the money around covertly through various shadow groups.
In the end, it's like laws against murder with guns, or laws prohibiting drugs or alcohol. They make people feel good, but accomplish nothing, or perhaps even make things worse.