Further nitpick:
>Secure from whom?
The only person who seems to benefit from the way the security model works on Android is App Developers/carriers/manufacturers/Google. The user abstraction on an Android device doesn't even line up with a human user of the device, but rather it lines up with applications and software on the phone. I have seen nothing that more obviously tuned fpr turnimg a general computing device into a passive scripted experience regurgitator than Android.
You do not get the ability to organize arbitrary data. You need an app. You don't have a consistent experience of a filesystem, shared across all programs. Instead, you have a myriad of apps that do everything they can to hide the implementation details from you.
This does not "help" computer literacy to be most people's first encounter with a computer.