This is a hybrid of a playlist and station and is explored in my blog post.
Bascially, it's a simple way to listen to music, add it to a playlist (for playing specifically good songs individually later).
Interesting blog post and nice ideas!
I will mark this topic as 'Unspecified' since it's hard to ever mark it as 'Implemented' with various ideas in it (normally just 1 feature request per topic) but of course I leave it open for discussion and gaining kudos. 😉
You might also want to search for the single ideas in the ideas exchange and give them kudos, for example Preventing Duplicates and Modifiable Thumbs up-down.