The Broadcast Flag and the War on Terror
One unwanted effect of copy restriction is that terrorists could conspire without ordinary people listening in. Right now there's a possibility their messages might wind up on Little Green Footballs the next day. Really effective copy protection might stop that.
Government agents could listen in but, even if we disregard those that apparently came from the Retief series, they probably couldn't keep track of the zillions of false positives.
Semiprofessional hackers could listen in, but <stereotype>they might sympathize</stereotype>