"Specifically, I'm thinking of the design and feature-richness of Apple's GUI toolkit. It was way ahead of every other mass market GUI design in the 1980s, even things like GEM (the GUI Atari used). ... in the short and medium term, the architecture was sheer wizardry which permitted Apple to cram a dramatically better GUI than Amiga into fewer resources. (just 64K ROM and 128K RAM in the original Macintosh)"
Sorry, having used both Amiga and Mac in the late '80s, I have to disagree here. Call them personal tastes, but I felt the 1-button interface of the Mac quite bulky, if compared to full right-menu 2-buttons paradygm of the Amiga. Both AmigaOS (pardon, Workbench, at the time) and MacOS had their examples of wizardry - after all, hardware resources were scarce at the time - but in the end the Amiga was the platform which got the most of them. The evidence is the *fact* that Amiga could emulate the Mac and even run its software full speed, while the contrary was not possible at all. There were many advantages with Amigas: public, draggable screens for instance (I saw that latest version of MacOS X has something similar... good thing to see, 25 years after), the ability to choose what files had a icon and what hadn't, the ability to switch without issues from a graphical to a shell-driven way of doing things... The Mac always gave me the feeling that it could somehow "understand" what I would have liked to do, and it was really amazing, but it also gave me the sensation that all my possibile actions were previously decided by Apple, and that I couldn't hack very much about them. The Amiga, on the other hand, was the total freedom of expression. Great times, the Eighties...