I think it's a combination of things - certainly nostalgia's one of them and the Amiga has some wonderful, original games and demos that are as entertaining today as they were back then.
I think the OS has aged incredibly well in some respects - it still (to me) represents the best fusion of technical underpinnings and user-friendly design. Things like datatypes, assigns, dosdrivers and the Amiga's simple way of installing software are still things I love about the OS.
Back in the day I knew AmigaOS inside and out and a lot of my daily use was a 50/50 mix of UI and the CLI - I just don't work that way with computers any more and to be honest, I kinda miss it.
I was also a big fan of apps like DPaint and Brilliance - in fact I still think they've yet to be bettered for pixel/bitmap art.
All change isn't necessarily for the better.
