yes, hashchaining is useful

I hope criminals keep thinking this, because it's flat-out wrong. Bitcoin is insanely traceable: every single transaction ever is immutably recorded in the blockchain. Of course, real-world identities aren't recorded in there... but at some point your average criminal is going to want the gains in an actual currency he can actually spend, and that's when real-world identities get involved, and that's when the law is pouncing. :)