Whilst I see your point, and I would love a major mobile device manufacturer to enter that space, there's a large barrier for Apple: the underlying operating sy

Whilst I see your point, and I would love a major mobile device manufacturer to enter that space, there's a large barrier for Apple: the underlying operating system is not open source. Whilst that remains the case, the question of security ultimately breaks down to Apple saying "Trust Us". Given recent revelations, that's not something that should be afforded to any company that fails to demonstrate a commitment to protecting the personal data of it users from everyone including itself. A 3rd party audit of the source would go some way toward building that trust, but falling short of a publicly available code-base allowing independent verification, I doubt it would be enough.