How do you figure? Currently, if I made a song on my iPad, I have remember which app I made the song in; so, I have go open up Garageband and see if it's there. Then, if it's not, I have go into FL Studio to see if I made it in there. A simpler solution would what I do on my Mac - I have a folder named "Song Demos" that store all my music demos from different apps (which I can have an overview of all my demos in my glance).
Also, if you're working on a project that involves mixed files (a Word Doc, a Photoshop file etc...), you can't group them in iOS & are forced to jump into applications just to view where your files are.
I guess it's not a big deal for people who just use iOS devices to consume media, but if you're creating, it's a drawback.