Do you ever sign a lengthy contract without reading it? Of course not, you say, and I'll call you a liar. Every time you click "accept" on those terms of services without reading it, you just agreed to a contract. So what did you just agree to let that Facebook Messenger App, downloaded over a billion times already, can do on your phone?
The blatant privacy violations that one billion people just agreed to here make for a bleak future. If you think it's ok that an app can record your conversations or video at any time without you initiating it, but freak out about the NSA, I don't even know where to begin. The cognitive dissonance displayed by those who love free as in apps, but seemingly hate as in privacy is amazing. Your first step in cleaning up your phone is deleting this app, and then reading the TOS of any other apps you use to make sure that you're comfortable with the level of privacy you're giving up in exchange for an app. I'd go so far as to say delete your facebook account too, but I know you won't.
Of course, all of this data is collected to make advertising more targeted in the end, but hand on your heart at what point did you ever see a facebook ad that was something you cared for? Do you think more info to facebook will ever make that better?
Update: I feel that it's important to note that iOS sandboxing makes some of these things impossible to do, such as make calls, without throwing an OS prompt up on the screen, but also that this is the terms of service you agreed to which you frankly shouldn't, even if how iOS works protects you from some aspects of it. You're agreeing to it, and that's what this article is about.