Alright, this might be vague, but I will start by saying that in general, this platform could be a lot more social, that's what people like, and it'd be a perfect opportunity to expand an already great thing.
1) Live Broadcasting - it's great that you can see what song somebody is hearing, and play it from the start, but I want to be able to TUNE IN to somebodies music exactly as it's happening, and hear what comes next.
2) Comments/Chats on Playlists/Streams - it'd be great to be able to say something about a playlist you're following or collaborating on, and if you're going to have a live stream, those listening could chime in and make suggestions, ect. It'd be like friends radio. What a BLAST, right? There's a lot that could be done there.
I think if I were any more specific it might not make sense, but you get the idea. More ways for people to connect through music, because ultimately, it's the best thing ever.
Also why are you keeping those following a playlist a secret? bummer!
Thanks for your services to our nation, what you're doing matters. Let's make Spotify great again.