What's the big deal?
I've been following Cafe au Lait for a few weeks now, and it really amuses me. Quotes like "the best Java can or should do is faithfully mimic the native user interface" and "the goal of a Java application is to fit in with other native applications, not to stand out" most certainly indicate that the writer is a strong proponent of a native look and feel, which is kind of bemusing. The Mac UI is shifting constantly, and the upcoming OS X release is supposed to feature a new UI (Illuminous?). Given the history of OS X for the past few years, and numerous native look and feels (Aqua, Graphite, Brushed Metal), it would appear that even Apple's UI designers don't consider the current state of affairs as the best. But i digress.
You need to be able to change the UI around really easily during development