we don't need to regulate cryptocurrencies but regulations can be also helpful with the adoption and growth of them or they can be restrictive and even prevent the adoption altogether. in the end it will come down to what they are regulating and how. for example if it is regulation of exchanges and if it leads to a more secure place where people can trade with less risk that would be a very good thing.
Perhaps the exchangers will become the place to do the money laundering? I mean still depends on the what kind of regulation they will impose on the exchangers. If it just tracks the transactions happening at the exchanger then it wont be much useful as our addresses still remain the anonymous. There are services like bitcoin mixers where we can get the anonymous characters unfolded and no will know we were the one who did that transaction. Correct me if I a wrong with this ? There Will always be different ways of making the whole transaction anonymous and thus keep it untraceable. This is as long as we do not transact in the bank accounts. However the later is still the same case as if today.
As we engage in crypto currency we also realize that this is a anonymous in nature the transaction is in your own risk, the only law that regulate crypto currency is trust make crypto currency proliferate because of trustworthiness people will invest.