This is a really good article. I’ve heard of cognitive load theory before and you’re completely on point to mention it with regard to the touch bar. If the bar wasn’t meant to be looked at, then it wouldn’t be in colour. Saying it is ‘merely’ an extension of the keyboard isn’t correct since I rarely look at individual keys. On a mobile phone, it’s different: you look at the keys and the predictive text section as you type. The screen on a phone is the keyboard and the interface; on a laptop they are discrete entities.
I think that what has to be admitted is that touch doesn’t solve every UI problem and in many ways creates new trade-offs. Saying everything must be touch because of some blind faith that ‘it’s the future’ completely misses the point.