Macworld’s interview with Tweetie creator Loren Brichter reveals a glimpse into the reasoning behind Tweetie’s departure from a standard UI:
Macworld: How did you approach designing Tweetie for the Mac? It almost looks like a radical departure from the standard Mac app.
Loren Brichter: Radical, yet not. It’s an evolution of UI concepts, many borrowed and extended from the iPhone. It fits in as a Mac app, looks and feels like one, but the navigation and functionality is next-generation. The drill-down is inspired by iPhone, it was important to be able to make it easy to delve into tons of information without requiring the app to sprawl across your entire monitor. The sidebar was particularly interesting to design. I needed a UI that worked well with exactly one account but also scaled to many accounts. Old school Mac implementations might have had a double set of tabs, or a Mail-style sidebar, or a tab bar with an account dropdown box. All of these are flawed. Some take up too much screen real estate, some aren’t good enough at providing at-a-glance badge notifications on a per-account-subsection basis. The sidebar design in Tweetie for Mac solves these problems in an extremely elegant and scalable way. It’s new and different, which is hard for some people to swallow, but somebody needs to push the envelope and try new things or we’re all going to rot in UI hell.