There are many approaches to building libraries that wrap HTTP APIs. For many of our officially supported SDKs we chose to build light wrappers around HTTP client libraries with a few added features to make it easier to work with the SoundCloud API. This approach has a few benefits. It guarantees a certain consistency and is relatively easy to maintain. It's also fairly future proof. Changes in the HTTP API do not typically require updates to client libraries.
Sometimes however, you might be looking for something a bit more feature-full, or with more abstraction from our HTTP API. That's why I was really happy to see that the great folks at SocialFolders built an alternative SoundCloud Ruby gem and released it to the public. You can check out their blog post about it or go straight to the source on GitHub.