Not sure how viable this is (might introduce too much UI clutter or add unnecessary "clicks" to access playlists), but wondering if any consideration has been given to providing the ability to add Categories (or folders) to the Playlist area.
I have tons of playlists (probably too many), and would be nice to have a way to categorize these so the list isn't so long and unruly at first glance. Being able to group playlists by genre (or whatever) would allow those users with tons of saved playlists to clean things up and organize into smaller groups.
You can already create playlist folders.
Right click the sidebar to create a folder