Hey! I'm one of the developers who worked on this project (the other being @JaredTMoskowitz).
We made this at a Hackathon quite a while ago and decided to ship it. Our next steps are trying to use the unfollowing information to eventually recommend twitter accounts we think you'll like. We're also currently building a Facebook version for unfollowing old fb friends.
To address the iOS 8 question, we built most of the code base in the first 24 hours, so it was hard to know what exactly we would end up with. Thanks for addressing this, we unfortunately forgot to reevaluate that decision!
Happy unfollowing!
Drift