From what I've seen of the latest Apple devices, they make sense to Apple if Apple wants greater integration between OS X and iOS, as in eventually having a single OS on all Apple devices. The new bar on the keyboard helps with iOS-style swipe gestures, standardisation on USB Type C means peripherals can target iOS and OS X devices, etc...
That's the only explanation that makes sense to me.
Perhaps that was a bit of a stretch, though both are protocol-agnostic, so switching from Lightning to USB-C in the future may not be as problematic as it could be.
That's the only explanation that makes sense to me.