What Apple is essentially saying here is that “judicious expressiveness” is allowed. A lifelike rendering style is encouraged.
A designer’s perspective on the macOS Big Sur app icons has given me new insight to the potential impact behind the shift. I was not a fan at first blush. I’m still not sold on all the changes, but I do have a better appreciation for them. Definitely worth a read.
With this approach Apple is legalising a visual design expressiveness that we haven’t seen from them in almost a decade. It’s like a ban has been lifted on fun. This will severely loosen the grip of minimalistic visual design and raise the bar for pixel pushers everywhere. Your glyph on a colored background is about to get some serious visual competition.