To me the heart of an OS is the file directory. In Windows this is Windows Explorer together with shortcuts to the desktop and Quick Launch. In Linux, this is similar with Home directory.

Steve Jobs decided the file directory was too confusing for Joe and Jane average so specified iOS to be directory invisible to the casual user and unreachable by the advanced user. Instead you operated with the OS through Apps. Each App has its own file types and sees no other.

Mr/Ms average seems to comprehend this method but it drives more seasoned users berserk.

Linux will never be an iOS for the directory challenged. Windows8 is trying to be more like iOS but with escape hatches for the directory competent.