Apple doesn't need outside ecosystem builders here; what is the business reason for them to add process expense, risk, and possibly incorporate timelines from other vendors into their supply chain?
As the many comments in this thread indicate, lots of people seem to feel Apple "owes it" to the world to open up. Happily, there is a (more) open ecosystem available with Android for people who value that. I don't think the tradeoffs Apple makes are perfect for me as a consumer, but I prefer them to the Android tradeoffs, and I can always switch when I like.