In reply to Justin Tadlock.

I guess the real question is who are you designing the customizer experience for? I'll be the first to admit that just mirroring API out to the UI is not a solution (you really want your users seeing floats? display: table-cell? pointer-events! no way...).

But I also know that out of the ~100 websites that I currently help design/build/maintain for my agency's customers, less than 15 of those customers actually go edit their website themselves (that's what we're there for), and they certainly aren't messing with customizer. Instead, I need to make it easier on my team of designers/developers to construct and maintain these sites for our customers. Right now, neither the WordPress theme format nor the customizer is really focused on making WordPress a great place for designers and developers to do their work.

Btw, maybe a way to approach the whole "one control to rule them all" concept without diving into the deep end is to design a parent control that can have these "groups" of simpler controls added to it using actions/filters so that you can continue working through the typography idea on its own, but with a broader scope at the back of your mind. Personally, I wouldn't mind working on a more comprehensive set of background controls.