I've seen similar ideas before and have seen that Spotify have closed the case on the internal messaging system due to low engagement. I get why that would be the case - I already chat to my friends/family/colleagues on about 12 different platforms.
I believe that Spotify could really benefit from a Recommend function. This could work in a similar way to Facebook notifications whereby somebody could recommend an aritst/album/playlist/track to one of their Spotify connections like they can with the Share function now. This would then pop up as a notification (possibly even push notifications if opted in) saying "Ronald Dump recommends you check out 'Artist/Album/Playlist/Track Name'" with a link directly to it.
The level of social engagement is low, though if the feature was widely used, this could be followed up with a Like/Dislike feature for the receiver to use to let their friend know whether they liked it or not.
On a similar note, notifications would also be really handy when a track was added to a collabarative/shared playlist by a friend. Something like "Your Friend just added 'track name' by 'artist name' to your 'playlist name' playlist. Check it out!"
I think these would really improve the social experience of sharing music with friends on Spotify without having to leave the app.
Updated on 2019-09-09
Good ideas! It's better to post each suggestion in it's separate thread. That way, users can vote on each one of your ideas.
For more info on how the Ideas Board works, click here. 🙂