I not one that cares about eyecandy persay, I'm all about functionality, that said. Why not simply make the volume buttons skip tracks while song is playing and device is locked. My idea is like this.

When device is locked, screen is off and music is playing:

1) Use volume buttons to skip tracks. One short press would skip/repeat a track. one long press would increase/decrease volume.

2) Two quick presses on volume decrease, would skip to previous track.

3) Use camera button as pause/play button. Long press of camera button would be 'stop'.

This would save developers a lot of hackery and time since its easier to implement.