In reply to Rick Gregory.

Yes, we definitely should rethink the admin area. But again, I'm not suggesting we shoehorn everything into the current customizer interface. As I quoted Helen above:

What if instead of opposing "shoving more stuff into the customizer" we supported "adding live previews to WordPress functionality"?

What I am advocating is that we develop WordPress in a way that all changes can be previewed and staged. The underlying Customize API provides the mechanisms for this. The current “Customizer” app (which heretofore is the only application of the Customize API) should not be considered the ultimate UI for previewing and staging changes to a site's configuration and content.