Wiz has historically favored performance over ergonomics in the extreme. None of it is open source, and to be honest even if it was it's unlikely most people would want to use the mix of Java+Soy+JS+jQuery-ish API.
Interestingly both frameworks are around the same age (if you count Angular 1.0), but Wiz was kept internal.
What Sarah is referring to is both a big shift in Wiz to get modern ergonomics and a shift in the framework strategy to avoid having two entirely separate frameworks.