> Also, if you solely receive and send bitcoin outside of an exchange, you can easily remain pseudo-anonymous in that anyone can see that wallet X has received Y bitcoins and send W bitcoins but without a person attached to the wallet, it's useless information.

If this thing were a big enough problem, the government could easily require you to provide a ledger of all the parties you've transacted with (Your wallet is doing book-keeping, how hard would it be for a legitimate user to enter a small memo for every transaction, anyways?)

Failure to provide a ledger, or for your ledger to fail to cross-correlate with that of your counterparty would, of course, imply that you're a criminal.

Unlike cash, bitcoin leaves a very obvious breadcrumb trail, that can, with a bit of legislature, be turned into an incredibly useful tool for LE.