1. Hiding your assets from those who have no business knowing what you have.
2. Facilitating discreet transactions
3. Reducing the friction in payments (avoiding/minimizing transaction costs)
4. Holding a non-dilutable asset as an inflation hedge
5. Retaining control of your funds (resistant to seizure, theft and mismanagement by third or fourth parties.)

A.The beauty of the situation is that bitcoin's biggest promoter is the U.S. government itself. By forcing Switzerland and other tax haven to relax their banking secrecy laws they have created a market need for a peer-to-peer cryptocurrency.
B. Know-your-customer (spying by the bank) laws also make bitcoin a favorable alternative.
C. The crackdown of online gambling, poker, and Intrade (prediction markets)
D. Asset forfeiture laws ostensibly for the purpose of fighting the "war on drugs".

Am I missing anything? feel free to add to these lists.