Dvorak frightens me in much the same way as people giving me new types of oranges to eat. It is a brave new world, and I may be a coward.

If they had such a head start, why have they failed so miserably?

I would agree, that visually NeXT had more in common with the Amiga direction than Apple. OS X is not based on any previous Apple OS. I'm not sure that Amiga was the inspiration for what NeXT was doing, but they did have the same user base (video/sound editing).

Linux users just haven't fell victim to the mass hysteria of solving a problem, which never existed. Apple designed an appealing desktop, and as their market share increased, Microsoft began throwing UI designs against the wall. Then people started buying phones and tablets, so designers decided no one wanted a functional desktop anymore. Gnome 3 decided to screw everything up, then Ubuntu decided they wanted everything screwed up in a different way. KDE made the same traditional desktop demand more resources, making it unusable.