People decide what they do with their own money and desires. I could buy new MacPro, but picked X1000, because its most advanced Amiga like system I can have. By using very nice Ubuntu 12.04 LTS, many of AmigaOS shortcomings can be covered on same machine.
Each to their own of course but if you want to run Ubuntu you could get exactly the same experience (well probably an even better experience) for less money with a x86 box and an Amiga sticker.
I don't really see the point of buying an NG Amiga and then running Unix on it, I know of one X1000 owner who uses Unix almost exclusively on his X1000.
It's like they're saying that OS4 is not up to the job so you're better off with running some other OS on your OS4 machine, this seems very strange to me.
I think Commodore did something similar with the classics back-in-day when they released x86 daughter boards for the 68k computers, also very strange IMHO.