Should I care about organised crime using bitcoins ?
I don't. Shame on me, I know.
On the contrary, the fact that organised crime will spend energy in using bitcoins ensures me that governments won't be able to control the bitcoin network.
Crime should be fought for what it is. A murder is a murder. A theft is a theft. But when a criminal is using a car, he's just a person who is driving a car. Fast cars are important for thieves, for they allow them to escape from police. Still, I don't think it would be a good idea to forbid the use of fast cars. It's the same old debate regarding the tool and its use. A hammer can kill someone, if it is used in this intention. Still, we don't ban hammers.
Therefore, I don't care if organised crime is using bitcoins. I don't care at all. There are other ways to fight criminals than tracking their expenses.