One "problem" I've observed with initiatives to make new kinds of computers is that eventually you want software on them. Some sort of x-nix compatibility layer will inevitably creep in and then the computer and OS just seem to become yet another compilation target for every popular GNU/Free/Open Source project in the world and then you're basically just using a weird window manager with weird compatibility issues and slightly out of date builds of the software everybody else is using (or local clones of the same).

Systems like the Amiga existed when the complexity and economics of making software for one kind of computer (thus making it unique or special) really worked out -- and even then most things were ported between a variety of platforms. It's very hard to create a differentiated platform and keep it differentiated long enough that it doesn't just get overwhelmed with the rest of the world.