I think that mobile devices offer such a personal form of computing that experience is of the utmost importance. The only way to truly emphasize experience is to be in command of both the hardware and software. They absolutely must be symbiotic in order to create the best device possible.
Further, while “control” often has a negative connotation, it’s important for quality. When you “open” your device and/or software, shit always finds a way in.
Apple is winning with this model right now because they’ve proven that have great taste when it comes to consumer electronics and the relationship of hardware and software.