FB isn't really alarmed... The majority of their revenue comes from their own app which they'll continue to be able to target you on because people give data to it willingly. They won't be able to use their partner mobile apps to display ads to, that was a decent business but obviously will become less valuable, but it wasn't that big for them. They are signaling to their customers that things are changing and to expect that they'll change dramatically. FB however remains with your real email address on file and lots of accurate data about you, with their SDK and other mobile apps their accuracy in data collection won't change a whole lot.

Because forced decision making is a barrier to tool use. For instance, imagine if every time you opened your IDE it asked you which language you're going to type in. You like your IDE to be work best with the language you're working in, so that's good. You're adding user choice here, so that's good. But the outcome is bad. Why is that?