Music, movies and other stuff I like to use on airplanes, subway and other places where I have no data connection....or perhaps in the future when I no longer have unlimited data and need to be frugal with what I use. Maybe back-up my laptop and other critical files, which I now have to carry an sd card/USB stick for, files that might be too large if not impossible to retrieve from the cloud in areas of weak or no 4G signal.
Storage is cheap (as this eventually will be), so why do I have to jump through hoops to manage insufficient storage? Why do I have to pay $100 premium for 32 extra gigs internal storage when a 64gig micro sd can be had for $30?
So what if I might be a digital pack-rat? It's not like there's an insurmountable, unnavigable mountain of USB drives cluttering up my house.