I would love to fully access the data on my phone. But of course it would also introduce security holes currently unimagined. Maybe someone can devise a secure sandbox model to enable this, but after Java's failure to resolve this problem, I'm not holding my breath.
Why is giving you a person, access to all of your data a problem?
The root cause is the complete lack of facilities to quickly and simply delegate capabilities to applications. There is no way to tell the OS, give this file to this application. Instead of trusting nothing, and providing the PowerBox facility to allow the user to do this, all the popular OSs just trust the applications with everything that the user has permissions to access, by default.
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If you want to pay for a purchase at a store with cash, you carry a number of units of currency... and you only give the clerk the appropriate amount, and you can count the change to verify the transaction is correct.
Giving you a person, access to your cash is a solved problem. 8)
There is no equivalent way to work with an application on mainstream OSs. This is collective insanity, which I've been calling out for more than a decade.
iOS works the way it does to make money for Apple. First it was to appease carriers to enable the devices to exist. Then it was to appease publishers to get content on the devices. Now it's to make that sweet, sweet app store commission. That there are benefits for device owners who are willing to give up their freedom is a happy accident.
Note that every stage you have described has been called "security". Security is inherently a multi-perspective endeavour, and the word gets abused by powerful entities looking to preserve their own security, likely at the expense of your own (eg the TSA). I do agree that end users receive benefits from Apple's security, but to insist that explains the whole story is hopelessly ignorant.
