I follow Anonymous News on Twitter, and I have to say that a lot of what the various groups do is good work. Whenever there's a protest going on anywhere in the world that involves armed government forces on one side, and everyday people on the other, there's a group of Anons working to take down government sites there, to even the playing field. Their news feed posts updates, photos and videos that most network and cable news programs don't, or won't.
Anonymity protects the various individuals involved in these campaigns. Some of what they do may be illegal, or may make them targets of those who own the sites they take down. I don't think anonymity should inspire fear. I think it's a logical choice, given the type of work being done.