Perhaps you're missing something. XIBs are arguably among the most powerful features of Cocoa. I built an app with a really complex, dynamic layout using them (look up "Panna" in the App Store). Working with an evolving design and changing team, with layout elements often changing and getting tweaked in tiny ways... Well, if I did the entire layout in code, I would have needed a full-time developer just for the ongoing GUI changes. I agree that dynamic layout support was weak pre-constraints, but it was still a much better development experience, and now you can do really complicated things without any code at all.
If you're just talking about some buttons in a toolbar, go nuts, but otherwise it's worth the time investment to learn.
I think there's a case to be made though, that using IB when starting out doesn't make you fully understand how UIViews work. So starting out I'd probably recommend you make your own views programmatically to know what you're hooking into.
That said once you get that base level of understanding, nibs and storyboards are huge time savers, and are the way to go.
While using storyboards definitely meant that I didn't understand things like how my root view controller got set up, I don't think it abstracts too much. Most importantly, using Interface Builder allowed me to explore the properties of views and get immediate feedback on how they're made. I still go back to a Storyboard when I need to figure out what combination of UIControl content settings I need.
If you're just talking about some buttons in a toolbar, go nuts, but otherwise it's worth the time investment to learn.