This is a security tradeoff with BRowsers. System security. Accessing files without valid permission will fail. And Browsers are really strict on accessing any files outside of the server domain directory. Any files you want I suggest including into the project files list at the project heirarchy(right click include on the file folder). Then at run time you can use AJAX to directly access the file.
If you want free roaming file access to android directory structure. There isn't one. Yet. As for reasons noted above. i think there is Cordova feature that let us so, but there is no implementation of it as of yet under any platforms.