This interesting talk about blocking tor and the arms race for privacy really opened my eyes. The filtering systems use more and more advanced methods. The current system that they are working against is in China connecting to every SSL connection to see what protocol that bridge is using. The goal is to make the Tor protocol indistinguishable from SSL or unknown protocols. The reason why it is so important is that in many countries people are censored or worse for disagreeing with the government, so Tor is the best method to allow free speech. Another critical reason is to combat surveillance which leads to blackmail, coercion, and discrimination among other dangers. This should be a concern more now than before because of the data Snowden released about the extent of surveillance the NSA conducts worldwide. This is an important consideration for any technology today.
Here is more information from the University of Washington on the Dangers of surveillance.