Having the extra slots on the Apple ][ allowed for there to be more uses of Apple's computer, and almost certainly led to more profit. It also did no damage since you couldn't use the slots to do anything to the computer that would cost Apple money. If Apple opened up, say, the licensing on the adapter plug on the bottom of iPads and iPhones, that would do just what Woz is talking about with the only impact to their bottom line being the licensing revenue for the plug. It would also allow more uses of their devices. I think there's plenty of places they could "open up" and still keep their river of money flowing in.