I'm surprised that nobody on this thread has commented on the real substance of this response. It has nothing to do with Apple brute forcing iPhones for the police (which it has done for years, with a simple court order) - but instead, is Apple making it abundantly clear, that if they comply (or are forced to comply) with the All Writs Act of 1789 to create this particular back door, then that opens the floodgate moving forward for all sorts of requests to add backdoors/decrease security.
It's entirely possible, that the FBI can then use this precedent to simply have Apple remove all security from an iPhone in pursuit of an active investigation, which can be done with a straightforward firmware update - which IOS users tend to do without much thought.
It's entirely possible, that the FBI can then use this precedent to simply have Apple remove all security from an iPhone in pursuit of an active investigation, which can be done with a straightforward firmware update - which IOS users tend to do without much thought.