I like the question, and I’d also like to know of resources for going IB-less. Usefulness (the “why”) is limited only by imagination. Off the top of my head, here are some possible reasons to program UIs explicitly:
- Implementing a better Interface Builder.
- Programming dynamic UIs, i.e., ones whose structure is not knowable statically (at compile/xcode time).
- Implementing the Cocoa back-end of a cross-platform library or language for UIs.
There is a series of blog posts on working without a nib and a recent description by Michael Mucha on cocoa-dev.