That‘s why I was careful to say that it should be
optional on those

Because I knew that some people are gonna be strictly against it.
But really, where would be the harm if it was an optional upgrade across the board (MBPs, MBs and desktop Macs). Some people hate it, some people find it a great addition to their workflow, and most people are somewhere inbetween these two extremes and find it mildly useful and superior to function keys but only by a small margin.
Why not give people the choice on every single Mac (including desktop Macs, with a higher-priced Magic Keyboard that sells parallel to the existing one). Those who hate it could then happily ignore it and those who consider it a step-up from the function keys and worth the price tag would have the option to get it on each of their machines.