Here in Germany there's a lot of talk that PRISM is ultimately a tool for industry espionage. The Boundless Informant world map shows Germany in bright orange. People are wondering: Is Germany breeding terrorists or is NSA simply interested in trade secrets?
Going by that logic, terrorism is a red herring. By making details about PRISM and NSA's hacking activities public, Snowden is undermining the US's ability to covertly vacuum up trade secrets, thus weakening the US industry. That's why the US government is freaking out. You can bet that German companies are now reconsidering using cloud services hosted in the US, or cloud services at all, or American (closed source / potentially backdoored) software at all.