The great draw of portable MP3 players is quantity.
I remember when my wife and I took a six-month backpacking trip back in 1999. We never even considered bringing an MP3 player, which might have had a whopping 64MB of flash memory, enough for about a hour of audio compressed at 256kbps. Instead, we brought a Discman and about two dozen CDs in a soft case. We grew extremely bored with those CDs and ended up jettisoning or trading most of them.