The judges felt that your proposal was very strong. Your UI visualization was especially strong. The judges agreed with your notion of UI efficiency, and appreciated that you illustrated this both positively, using sample Roundup screens, and negatively, using Bugzilla and Jitterbug counterexamples. They also strongly agreed with the idea that navigation and search are not separate modes, but actually the same thing, search being just navigation of a constrained dataset.
Issue tracking is basically a guided conversation.
Email is the de facto medium for these conversations. Roundup sees email's limitations and untapped possibilities clearly, and articulates a clever alternative.