The thing is: users explicitly allow facebook to do that when they agree to ToS, just as they allow it to store their personal photos, statuses, and messages.

It's not exactly without consent

My old manager wanted me to install WhatsApp. WhatsApp wanted to access my phone's address book so that it could upload all of my contact info to their [Facebook's] servers. I denied it, and it refused to work. I didn't want to share my contacts - I just wanted to communicate with a specific set of people. The only workaround I could find is back up and delete all my contacts before letting WhatsApp rummage through my address book.

I wouldn't say this practice is very "consensual".

You wanted to use the app. The app makes the rules. Either use it or don't. I don't see how they had a gun to your head.

Sure, as Congressman Sensenbrenner said, “Well, you know... nobody’s got to use the Internet”

http://wapo.st/2nPh3JN

Everyone in the contact list didn't provide consent. Facebook better understands the privacy implications here more than individual users so I don't see anything wrong with placing most of the blame on Facebook.

It pretty much was the entirety of the Facebook app's life. And it only somewhat changed when Google introduced permissions where the user actually has to opt-in (post app install).

Going to a doctor implies consent to have your contact data shared with Facebook?