It would be great if the Blender icon fitted in with the default macOS design. I know this chat is about what the default logo should be… but to throw my hat in the ring, I have created two icons for Blender which I use on my Mac - Orange for LTS releases and Blue for Beta, Alpha releases.
If you fancy using them, you can download them from this DropBox folder:
https://www.dropbox.com/sh/is7yd2vleo1j36a/AABT6gPbHHXDg1PSOTrOyYR_a?dl=0
Really simple to swap. ‘Get Info’ on the Blender.app, then drag the .icns file onto the icon at the top of the ‘Get Info’ window.
Enjoy 