This is probably due to the fact that the previous models had 2 connection modes, MTP & MSC. MTP mode is what was used with WMP & saved the playlist file with the .wpl extension. This file would be stored in the Playlist folder on the device.
M3u format is the extension used with MSC connection mode. This format playlist must be stored in the Music folder (or folder wher the audio files are stored). The newer players are MSC-only mode devices.
