Possibly, but just for the sake of an interesting discussion, what is there about this particular blatant “It screws users over but it's good for Facebook” move that is different than all the other moves they’ve pulled?
But this is another ballgame. What they've done here is effectively hijack a completely unrelated and ubiquitous communication channel — without any action on my part, and without giving any indication of doing so!
I don't even use Facebook, but since I created a Facebook account at some point in the past, they potentially have access to my inbound email traffic. That's just absurd and stupid.
It doesn't seem to be clear, as I write this, exactly what is going on there and how much is completely automatic/without consent vs. how much was "expected" behaviour. It's pretty clear that a lot of people aren't happy about it regardless, though. Even if some contact originally got onto your phone via integration with a third party service, that could have been years ago. If you weren't aware that the contact was only remaining there/unmodified because the third party chose to leave it that way, it's understandable that you might be upset if that changed without warning after a long time.