Thinking about how to implement this interface, I also wondered why all mp3players had such plain playlist functionality! I like the ability to chuck a bunch of CD's in a multi-CD cd player, and then play the CD's in random order. In such a way that the cd player selects one of the five CD's at random, and then plays the entire disc. This continues, until all discs have been played. No mp3 player could do this, so I decided to add it to mine.
The first usable version (0.9.0, named 'mp3player', how's that for originality?) reared its ugly head in august 1997. Since then, lots of things have changed.. You can read the ChangeLog supplied with the source if you are interested in it.