I hope people will use Spotify as a case study in how to fuck up a UI over time. The service itself is fine, I quite like some of the music it finds for me on discover, but the UI is on a slow death march towards complete uselessness, and some features have
always been hopelessly broken (queuing).
From a business standpoint I find it fascinating. It's about as perfect as an example it gets of "if it ain't broke, don't fix it". Music player UI is a solved problem. At some point they should've just said "welp, don't need a UI team any more" and just never touched it again, but that would mean people admitting they don't really serve much purpose. About as pure an example of a "bullshit job" as is possible.