Yes, a dark icon would match Blender’s interface better (which was my motivation to propose a dark icon in the first place), but this would not conform to Blender’s logo guidelines.
Also, I would use a colour gradient to match the appearance of macOS system apps like Safari.
This version uses a gradient close to the one used in Safari’s app icon.
App Icon + document icon for Blender files
I think this is a good way to conform to the logo guidelines and be a good macOS citizen. I have submitted a patch for review here: https://developer.blender.org/D12978
(I am going to make this version and all other explorations I posted in this topic publicly available later.)