File system access on Android is possible if rooted and in a limited fashion with the correct permissions... I think that AppGameKit just doesn't mess around with dynamically adding those to keep things simple. Makes sense to me as there is limited reason to be accessing the Android file system (unless you are making a file explorer / launcher.) The "correct" Android way of doing things is to set up your app as accepting certain actions from other apps, which may be a bit more complex than is appropriate for a games-focused solution like AGK.
Using AppGameKit v2 T1 + T2
Systems: Primary: Mac OS X 10.10
Secondary: Windows 7