Horace Dediu:

Seen from this perspective, the architecture of their proposed campus makes perfect sense. If it was a divisional structure then each division could live in its own building or campus. In fact, each division would not have much to talk about to any other division. But as a functional organization Apple needs to move people quickly between projects. It needs to re-configure itself frequently. Being in the same building means they can do this much more efficiently.

I hadn’t really thought of Apple’s new campus design in these terms before, but Dediu makes good sense here.