Last week the former US "cyber czar" Richard Clarke called the FBI out directly for doing it solely for legal precedent, and stated that virtually no one even in the gov't were on their side:
http://arstechnica.com/tech-policy/2016/03/former-cyber-czar... >>Clarke noted that Comey and the Justice Department were not getting support in their case from the defense and intelligence communities. "The Justice Department and the FBI are on their own here," he said. "The FBI director [Comey] is exaggerating the need for this, and the Attorney General [Loretta Lynch] is letting him get away with it."<<
But the weird thing is that, from the beginning, most legal experts thought the likely outcome would be that All Writs would be found too broad, so the FBI had to have been suffering from some hubris + bad legal council. So maybe someone with enough muscle finally called them out on it?