Is group polarization always bad?

In chapter 3 of Republic.com 2.0 Cass Sunstein talks about polarization on the internet. He explains that the internet allows groups of people that may not have the opportunity to interact to be able to talk and communicate with each other. He gives examples of terrorist and hate groups being formed and grown online. He believes this is dangerous because when individuals of similar thoughts and beliefs come together their opinions become more intense. He gives only a few situations when group polarization benefited groups and society. I think his approach to group polarization is too negative because it seems like he focuses mainly on the bad examples of it. One recent event that I feel like is a good example of this is the revolutions in the different counties such as Egypt. The citizens were able to form groups and set up protests all with the help of social networking and the internet. Most likely, they were also able to see that others had the same feelings that they shared which amplified the groups beliefs and pushed them to take action.