I hated the butterfly keyboard, because mine failed, and a keyboard failure on my work machine is completely unacceptable. I vowed to stop buying Apple completely if they didn't fix it, and sure enough, typing this on the 16" 2020 MBP, with its classic scissor-switch keyboard, showing every sign of being just as durable as every other Apple scissor keyboard I've ever had (a considerable number).

But I don't think it's entirely fair to just call that failed experiment the pursuit of thinness at all costs. Scissors are a bit mushy, you can move your fingers around on a keypad and feel them wobble. The sound is kind of dull, the action lacks a clean tactile break.

The butterfly keyboard felt great, to me at least. Crisp, clicky action, rock-solid pads: to my taste, the tactile experience is superior. If they had found a way to make them absolutely reliable, I'd have called it a win. Although the square arrow keys and lack of a physical escape key were ergonomic disasters, that's orthogonal to keyboard action, they could have fixed both of those things while sticking with the butterfly switches.

These are ultimately aesthetic considerations. Someone else certainly prefers the sound and feel of the scissor switches, I respect that, I just disagree is all.

So I don't think shaving a half millimeter was the be-all and end-all of the decision to iterate on the ultimately unworkable butterfly keyboard design. I imagine Jony Ive thought it was a nicer keyboard and just spent more time trying to make it work than was really justified, especially since it proved to be impossible.