There was a coin called community coin that did some of what's being proposed for ethereum. The dev "lost" a massive amount of coins on a "broken hard drive". He blacklisted the address containing them with a dodgy bit of code and expected everyone to trust his solution. Nobody trusted the coin any more and it crashed in price, then slowly died.
Blacklisting the address with the drained DAO ether in will destroy trust in ethereum. Can anyone trust the code to blacklist them will keep them blacklisted until a rollback? Will people worry that a hacker might find a vulnerability in it?