Perhaps a better example is in order.
Imagine you are a meth dealer from new mexico. You have $250,000 cash. You use that cash to buy mining equipment, which earns you $250,000 worth of bitcoins.
Can you now go to a car dealership and buy a new ford mustang? Can you buy a house? No, because now instead of being a meth dealer with $250,000 cash, you are a meth dealer with $250,000 of bitcoins. I don't see any problems solved here, except for the fact that the bitcoins are a lot harder to take away.
Oh and I don't think the police would bother with IP addresses and the like, they will just catch you selling meth, see that you had no legal source of money to buy the mining equipment, and take that, and anything you would have bought with the bitcoins.
Uh right. You could just buy bitcoins directly with the $250k from localcoin places, or whatever.
But, lets say you have 2.5k bitcoins you got from selling meth on silkroad. Some of those buyers might have been feds. So what happens if you spend the btc in an identifiable way? Then the feds can trace the transactions through the blockchain.
Or suppose you're the guy who hacked mybitcoin or pulled off some of the other major heists in bitcoin history?
Instead of just loading the btc into MtGox - you buy miners from China or somewhere, generate 'clean' coins with no 'history'.
Probably not really worth doing, but paranoid people might want to do it.
