The key to the Mac therefore becomes that which the iPad/iPhone isn’t: an indirect input device. The keyboard and mouse/trackpad are what define the Mac. The operating system, the apps, the UX, are all oriented around the indirect input method. The iPhone’s capacitive touch brought about the direct input method, a third pivot in input methods (first was mouse, second trackpad/scroll wheel). Each pivot launched a new set of platforms and the Mac is the legacy of the second. (…)
The touchbar coupled to the other two inputs is a totally new way to interact with computing products. It’s not an “easy” interface as it’s not direct manipulation. It remains indirect, a defining characteristic of the second wave. Indirect inputs are powerful and lend themselves to muscle memory with practice. This is the way professional users become productive. The same way keyboard shortcuts are hard to learn but pay off with productivity, touchbar interactions are fiddly but will pay off with a two-handed interaction model. They are not something you “get” right away. They require practice and persistence for a delayed payoff. But, again, that effort is what professionals are accustomed to investing.
Horace Dediu perfectly nails the purpose of the Touch Bar: an indirect, context-aware input method that perfectly fits into the existing UI model, while enabling a whole new class of interactions.via asymco.com