Cash, laundering, shell corps; they have none of these properties.
See: parallel construction.
Bitcoin or not, if the technology existed to identify "darknet kingpins", the technique wouldn't show up on the open press.
As I already stated, parallel construction is completely unnecessary since everyone is already aware that the blockchain is a comprehensive public record of all bitcoin transactions. What secret technique could the government have that could give them more information than is already available for everyone to see? There isn't any more information beyond what's inside the ledger except for the link between wallet and bank account which everyone knows the government is capable of establishing.
As soon as Bitcoin became clearly successful, it also became inevitable that things like Monero or Zerocoin or Coinjoin would be invented. Once the genie of distributed e-cash has been let out of the bottle, it not merely can evolve but will evolve.
So in exchange for a brief period of visibility through Bitcoin, they would have permanently and irrevocably damaged their ability to spy via banks, Western Union, PayPal etc (entities which they pwn lock stock and barrel) as usage diverts to anonymous currencies (Bitcoin with extensions or mixes, or anonymous coins).
Assuming "much, much harder" isn't hyperbole, could you elaborate on this please? I'm interested in the tech aspect. The existing anonymous solutions I've looked at are all more complex and difficult to grasp than the simplicity of bitcoin's global ledger.
Hey, look at all this bad stuff! We need more money to fight it! Also, we can't tell you what we're doing to fight it, because then it wouldn't work, so just trust us, ok?
*Note: I don't actually believe this, and I don't own a tinfoil hat. Just an amusing thought.