Security researcher The Grugq:
Is the FBI playing politics? Yes. That is kinda what they do. It is what they always do. They are being extremely cynical in this case. They have selected a case which will cast the tech vendors in the worst possible light. The FBI has been planning exactly this for a while, waiting only for an attack that would provide the pretext.
An interesting list of facts about the San Bernardino shooters, their tenuous connections to ISIS, and what information the FBI already has gleaned from their personal technology.
(Edited to remove note about iCloud backups not being encrypted.)