The neglect of markets where they've had record sales the past year or two? Not to mention, the massive increase in mobile devices weighing into the equation. It seems a little off to me.
...which is further evidence of the amazing foresight Apple had in basing macOS on an open-source core (BSD): it means Apple doesn't need to expend resources on maintaining critical functionality that isn't central to their profit strategy (e.g. BSD userland) (and it's why I believe the open-sourcing of key parts of the NT kernel and userland will happen eventually)
NeXT did it, not Apple.
And the goal of the time was just to help bring UNIX software into NeXTSTEP as they were competing against the likes of Solaris for market share.
https://www.youtube.com/watch?v=UGhfB-NICzg
The whole NeXT architecture has very little UNIX on it.