Good post, definitely feels like this is something that needs looking at after (or as part of) the next major update — which I assume is going to be around ‘outside the home playback’. Particular as that version/release may solve some of the playback syncing needs/issues.
Below is a bit of a starter for ten / summary of some of the more requested playlist features and a couple of my personal thoughts:
Currently you can only move one track at a time which makes the rearranging of large playlists cumbersome and annoying. Especially as playlists by nature often have 3 or 4 tracks that group nicely together nicely, that you may want to move together. It’s also often the case that you don’t want a newly added track to live at the end of a playlist, which makes the ability to quickly select and move multiple tracks even more vital. The ability to move sections of one playlist to another is ana advanced version of this. Ordinals (playlist track numbers) would also help in terms of dragging or reordering tracks to a particular position.
Currently due to the way that tracks are added to playlist (local vs streaming, different versions of the same album, if you cancel or pause your Tidal/Qobuz subscription, tracks disappearing from a streaming service) it would be useful to have a means, automated or otherwise to tidy up these orphaned tracks.
Folders — calm down, I’m not talking about the local filesystem 
But tags (in their current form) don’t work for playlists — at least for me and it seems many others. I expect this is partly due to personal playlist being, well personal …I don’t want to tag them by a generic theme, style, or mood and partly due to the (smaller, relative to albums) number of them. For me it makes more to treat them more as a nested archive where they can quickly be filed and found.
The ability to sync back to Qobuz/Tidal is obviously high on many people list as seen by the numerous feature requests for variation of it [1,2,3,4,5,6]. Short of full integration some level of automated Soundiz integration may be a useful stop gap. But this really does feel like functionality that should be built natively into Roon, at least for it’s two main streaming platforms (Qobuz/Tidal) without having to reply on 3rd party platforms and additional subscriptions.
While not a ‘core’ feature in the way that native Tidal/Qobuz might seem to be. The ability to export (and import) a playlist to/from Spotify does feel like a really useful feature given the prevalence of Spotify playlists out there in the world. If a music magazine or blog makes up a playlist 9 times out of 10 it will be shared/presented as a Spotify Playlist on their site, if a friend shares a play list with me, 9 times out of 10 it will be a Spotify Playlist. If I want to share a playlist with someone, then again Spotify is probably the simplest way. Like it loath it, Spotify is a primary means of sharing playlists in 2022. And yes, I can do this manually with Soundiz, but I’m talking about how Roon could be improved as a product — not what it does (or doesn’t do) today. This wouldn’t need to be built to the level of a product like Soundiz, there is probably a sensible halfway house where you could add a Spotify account to Roon for the purpose of sharing playlists and no more.
Before anyone throws too much scorn on this idea, it’s worth remembering that one competitive edge Roon has over the streaming platforms own apps, that may help keep it thriving long term, is that it’s not tied to one streaming service or audio hardware platform. It’s precisely because of that difference in business model, that it can do things like build in a Spotify import/export feature (if it wanted to) without worrying that it’s cannibalising it’s own market share. In short Roon doesn’t have to worrying about keeping a walled garden to maximise clicks & plays, instead it can look instead how to improve the product for it’s users wider needs and use cases.
Talking of syncing, a minor thing but the Excel export option doesn’t seem to include the original playlist order (ordinals) as a column. The Soundiz export does keep the natural order, but it doesn’t include any other information.
There’s also this thread (created post 1.8) that has tried to compile a bunch of playlist issues: