Have you used the previous generation of MP3 players? I had one with a tiny LCD screen that would only fit half the song title (no space for the artist). To go to then next song, you had to press the "next" button (which makes sense). Except that action would take at least 0.5s. You press next, you wait, you see the display refresh with the next song's partial song name. Not the song I want, press next again. Very quickly, to skip 10 songs takes 10 seconds of effort. It was a painful device to use.

The iPod cam with a large screen and a click wheel. I could find songs on it. That was a revolution for me.

MP3 was the enabling technology (if you can't fit many songs on a small device, then this is moot).