The obstacles so far:
- Politicians only seem to do it if they are in tight marginals
- Unions / Big business donations should be banned (according to the talking head)
- Even in the US - where parties are less controlled - they are finding that support networks can be organised to oppose individual policies
- The Internet has the potential to degrade politics (passim here) - though Obama was able to spend half-an-hour getting his message over on YouTube
- Single issue pressure groups and petitions (trans: applied idiocy)
The view that a move towards microdonations would improve the quality of public life was largely uncontested. I'm not sure I'd contest it myself - but I think it needs examining a bit more.