I wish BTC is not used for illegal activities though it is a currency. Legal and illegal activities require money. It depends on who uses the coins. Lets utilize the bitcoins only for good purposes as it was created to benefit all and lets bring more fame and name to bitcoins and its founders.
Such kind of question should to be in politic section I think. Bitcoin is just money as dollar and euro. Therrorists are making their things and wars with dollars, so what stops them to use Bitcoins as well. In bitcoins huge transaktions are not visible for govenments and world security, so I think Bitcoin it's perfect currency to use it as ever someone wish, even illegle.