During a typical 2nd Amendment[1] debate ("flame war", really) a common argument was raised about how various "big, modern weapons" required a different set of rules. Regardless of how one felt about people having "small" (i.e. traditional arms with which society has experience), surely it must be obvious that "big" (new, unknown) things like nerve gases or atomic bombs are so dangerous they must be kept from civilian hands.
Technology eavesdropping in new ways is a similar "forbidden knowledge". While it may not be a weapon itself, when it becomes simple and cheap enough that containing the forbidden knowledge becomes impossible[2] we face the potential disruption of some of the very foundations of society.
The question isn't if the average person will gain access to cheap and powerful eavesdropping technology, or weapons as powerful as atomic bombs, or even worse technologies that we haven't discovered yet. The question is if society will be ready for when those technologies grow and become a cheap commodity.
The general purpose computer already did this, and other electronic devices like the one mentioned in this article are experiencing this transition right now. Biotech seems to be ramping up and I suspect we will see the biotech equivalent to the "cheap personal computer" in the near-ish future. The point is we, as a species, really need to learn how to deal with these technologies now, or a future "mass shooting" might instead be an "engineered plague" or "20 kiloton bomb".
How do we deal with these threats? I don't know. But I do know trying to keep technologies bottled up as "forbidden knowledge" is at best only a delaying tactic. I suspect that "fixing most social problems" (racism, extreme poverty, etc) is probably a prerequisite. I personally like Roddenberry's idea of fixing most of the basic physical needs with technology; it won't fix everything, but it would probably be a good start. Unfortunately, it is easy to succumb to a defeatist or nihilistic attitude when faced with these problems. Even Feynman thought[3] the success of the Manhattan Project necessarily implied that civilization "would all be destroyed very soon anyway".
For me, I try to remember that we can't predict change[4], and worrying about things we cannot change is a waste of time and energy. Big problems grow out of small problems, so I focus on those small things that I can change. There is a real risk that technology will happen faster than our ability to assimilate those technologies, but we should try anyway, because the alternative is to give into natural selection as yet another species that didn't adapt to its environment fast enough.[5]
[1] This post is not about the 2nd. Please, there is no need to re-open that highly-charged debate.
[2] "information wants to be free", or at least hard impossible to contain.
[3] https://www.youtube.com/watch?v=Bgaw9qe7DEE#t=1114
[4] See James Burke's ("Connections") non-teleological view of progress
[5] aka the speciation of humanity. I highly recommend Bruce Sterling's exploration of this type of "end result" for humanity in his novel Schismatrix[6]. (this is where my username ("pdkl95") comes from...)
[6] http://en.wikipedia.org/wiki/Schismatrix