Re FaceTime, I recently read an unsubstantiated but plausible comment that they'd run into patent issues that caused a redesign that caused issues open sourcing it.
and according to someone I heard on a podcast, many of the engineering leadership heard the open sourcing comment for the first time while Steve was up on stage as well.
Not sure which particular episode (you might be able to find it by looking through old shownotes) but this was mentioned on Accidental Tech Podcast, I think by John Siracusa (of really long MacOS review fame)