Facebook has a history of starting with opt-in and then making it opt-out and then over time making it harder to opt-out. It is a well established pattern.
Honest question, I don't use Facebook so I can't tell from experience.
(I see what you're trying to say, that people are forced to install two apps instead of installing one - I just disagree that having two separate apps is "forced" while having apps bundled together is "choice")