Even if you don't encrypt your communications, can you be sure that NSA will not store your data indefinitely? Sure, they can pass the raw unencrypted data through their system, parse out the important bits, save them in a database with a unique key for you and then throw away the raw data. Are you OK with that? They have lied in the past and might even keep that raw data as well. How will you know?

IMO, best bet is to keep it all encrypted. It sounds like an attempt to scare people into leaving their stuff open.