Honestly, this list of features is really impressive, I'm really starting to see what made AmigaOS so special for so many people, and I'm a hard-line *nix gal. AmigaOS seems really unique, in that it's an especially lightweight, responsive, yet structurally clever and well thought through system. It must've felt light years ahead of everything well into the 90s. This is definitely making me want to upgrade my A500 to Kickstart 2.04 or 3.1 to get these features.
AmigaOS was far ahead of its time and really a treasure trove of cool features. Not just on the UI side, most of its contemporaries didn't have loadable and unloadable drivers, pluggable file systems, etc. It's amazing all this even worked without memory protection, but almost all of it did work.
I was a teenager at the time so I got to play with it when it was new. I had the privilege of learning how to code on my Amiga 500. Sadly it was in AmigaBASIC and later AMOS Pro (I even bought the compiler for that) and I never got to using real programming languages until the Amiga was already defunct. I find myself going back now, though, and admiring the OS interfaces in context with much more knowledge. The UI APIs were very lacking compared to today's toolkits, but for the time they were really next level.