Clandestine law breaking, once revealed, can make a mockery of the law and demonstrate difficulties in its enforcement. And more recently, the revelations of homosexuals who have served with distinction in the United States military despite their service being illegal have helped prompt a change in the military's policy on gays. For these two groups of people, taking the law into their own hands probably expedited legal change. But taking the law into ones own hands sometimes has the effect of tightening the very law one wishes to have repealed. Many a vigilante has wound up in jail without advancing their cause.
Cautious consideration is advised before one does something illegal to prove a point.
And the same can be said for doing something anti-social to prove a point. In order for the Internet to develop into a communication medium in which freedom continues to reign, it is important that all Netizens act responsibly and consider the affects of their actions on the community as a whole. But if behavior in the physical world is any indication, this is not likely to happen.