The .M3U playlists are inadequate for modern usage.
What I'd like to see a playlist do is:
- be able to refer to files in a directory tree under the current directory, either creating a virtual folder or virtual folder tree. This would let me create a playlist named "all" or "classic" or "rock" or "Queen", etc.;
- be able to cause PMS to stream the entire contents of the playlist as a single file so that devices that cannot do gap-less streaming of media over DLNA can play albums such as "Dark Side Of The Moon" properly.
I don't see any need for PMS to use the .M3U playlist format if that format has security issues or other design issues that get in the way of the above features.