Often it's just as much about hitting back as hard as you can. Now you can argue the merits of that, but we have crossed a major threshold here: The internet has taken down the websites of two of the largest credit providers in the world, two weeks before Christmas.
If that isn't an exertion of grassroots power in the internet age, I don't know what is. The implications are boundless. Visa, and Mastercard probably didn't think twice about canceling Wikileak's payments. I doubt their risk assessment would have been the same if they had known this would result.