I constantly edit playlists. It's become a hobby of mine. It's like being your own personal DJ. I have well over 100GB of music so when I create playlists I don't always know all of the songs I'd like added to that playlist at the time I create the playlist. I'm constantly rediscovering songs/albums/artists in my collection, so I'm always updating several playlists as I listen to my music and I realize what songs would be perfect for certain playlists.
I typically create playlists by "feel"/"vibe" or certain subcategories.
For example I can have the following playlists:
"Singalongs" - for songs I know by heart and can sing/rap to.
"Gaming" - typically for background music when playing action/shooting video games. Upbeat/intense stuff.
"Underground" - a selection of Hip-Hop that isn't considered mainstream.
"Lyrical" - songs that have lyrics which impress me
"Lounge" - songs that would make good background music for kicking back. Smooth/mellow stuff.
"Love songs" - self explanatory.
"Foreign" - songs in languages other than English.
I could go on and on, but these are just a few examples. I've built many more playlists in the past that I've since lost, which I will attempt to recreate.
But you can probably see that there are many songs that would naturally fit into more than one of these playlists.
Whether or not this feature is added, I'm still super happy with the PA experience. It's just another thing that'd make the experience better in my opinion.