The FBI has offered to help a court in Arkansas to break into an iPhone. Apparently, they want to show that they now have the means to invade the privacy of anybody who uses an iPhone. It is hard to imagine any reason, other than to provoke widespread intimidation, why they might be doing this.
Our government needs to break internet security in order to engage in mass surveillance. The goal is transparency for citizens and opacity for government. The focus on compromising privacy also helps distract the public from the poor job being done in preventing terrorism, even when encryption is not involved, and even when government has been tipped off about hostile foreign agents. Breaking into phones might help in court, after a terrorist attack. It may also make law enforcement appear more competent, after the damage has been done.
Most Americans do not like the idea of mass surveillance of everybody, all of time. Apple is working on a hack-proof phone (security built-in), which would help to justify the cost of the device and counter the impression that the FBI is creating, of an iPhone that's vulnerable to snooping. Mass surveillance is difficult to justify for moral and legal reasons, but also for commercial reasons. All of these - moral, legal and commercial - are valid reasons.
The Feds use the litany, pedophiles, drug lords, and terrorists when arguing for a backdoor that would enable them to intrude into our privacy. Words never used in arguing for breaking encryption are dissidents, activists, protesters. Loss of privacy makes political opposition far more difficult and far more risky. However, for the party in power, loss of privacy also means grater political stability.
So far there is little evidence to justify compromising security. Electronic technology may be used for illegal purposes by some, but so is a lot of other technology used for illegal purposes - guns, for example. There is no plausible reason for breaking privacy so as to enable mass surveillance. Probably the real reasons are political.
Thanks to @dudedave for the link to this video discussion of Privacy in the Digital Age.