It's a great idea, but it would take two terms just to make that proposal stick. It's going to take a lot more work to take money out of politics. Signing some papers and walking away won't work.
Some people call it the "Green Lantern theory of presidential power" -- that for one person with sufficient purity of intent and force of will, anything is possible. But the President doesn't get a magic ring of cosmic power, and the American political system was specifically designed to prevent rapid, radical change without comprehensive and unified support from all three branches.
Larry Lessig, George Washington and all other figures are/were human beings like the rest of us; it's only other people which catapult them onto pedestals. I think we should take stock in the coming socio-political fight for social justice, which needs a strong and wise torchbearer, so that it does not devolve into a French Revolution, but instead an insurrection in the spirit of democracy's promise of continual revolution. Because without a equality functioning across-the-board, history has shown time-and-time-again, that people inevitably seek country justice if city justice doesn't work for them. (It's not "right," but it's human nature.)