"Protect our trade craft" is a statement a surveillance outfit, not a law enforcement agency, makes. That's the terrifying disclosure: The FBI just admitted they aren't interested in law enforcement, they are interested in espionage.
So basically, a backdoor being a security threat to everyone isn't a hypothetical concern: It is one directly stemming from existing problems in real life, right now, based on the last iteration of this bullshit argument.
Let's be clear: Logjam exists as a direct result of forcing weaker encryption on export in the 90s, thus allowing people to use lesser SSL encryption for compatibility sake. That allowable downgrade is exactly the vector this attack uses.
To quote the article:
Another HTTPS vulnerability has started to make its rounds earlier this morning. Dubbed Logjam by its researchers, the vulnerability stems from the US's encryption export mandate back in the 1990s. This particular vulnerability, in the transport-layer security layer protocol, breaks the Diffie-Hellman perfect forward-secrecy. Susceptibility to the vulnerability is depended on servers and clients supporting the DHE_EXPORT encryption scheme, or using a key less-than-or-equal to 1024 bits.