Charles Stross herein presents a conspiracy theory that I'll admit having considered, at least in part, but hadn't taken seriously enough to post:
The NDAA and SOPA are designed to provide tools to counter future ArabSpring & Wikileaks type events in the United States, fueled by online social media and the worsening of the housing crisis.
Copyright is just a distraction. During the revolution they want the infrastructure in place to block access to foreign coordinating sites as well as the ability to round up suspected dissidents without charge.
On some level, it doesnt really matter whether or not this is a concious desire - these bills will do what they do.
SOPA, NDAA, and the revolution