The world is not better because of Twitter or Facebook? They played a role in the recent revolutions and help people connect with family and friends. Why do you think these governments tried to shut down the internet?
They may not have been helpful to you but to others they are.
This is really mostly MSM/blogosphere hype. These revolutions started when people set themselves afire, and risked their lives confronting the army/police. FB might have helped (Youtube probably even more, Twitter almost trivial) but in the same way that a cellphone would.
Governments are now using social media to track dissidents as well, so it's not at all clear the net effect it positive.
Agree with your second point. But Twitter helped spread the YouTube videos so I doubt Twitter is trivial. Communication, whether it's the Internet or cell-phone, helped the revolutions by connecting people and organizing them. But yes, we don't know the net effect and I think it's impossible to know.
They may not have been helpful to you but to others they are.