I don't think it's worth the additional complexity and having a "negative" element on the user interface. It's not only about the engineering and sucking that l

I don't think it's worth the additional complexity and having a "negative" element on the user interface. It's not only about the engineering and sucking that last bit of optimization from a technical perspective, it's also about creating a product/service that people love and embrace. Something with a negative-though invoking elements like a dislike button wouldn't be in favor of that. Spotify is a big company and I'm pretty much sure that they've thought about adding it multiple times throughout years. If they haven't, there must be a reason.