As a Japanese(-American) I can tell you why this project failed and more broadly why Japan's computer industry has failed outside of vidja gaemz (and that too is on its way out).
So why did the Japanese fail? It's very simple: Lack of cooperation. The article describes the project "was a collaborative effort of the Japanese computer industry" but the results could not put any more mud on that thought.
Japanese companies HATE cooperating, they will not create nor utilize common standards nor share knowledge with each other. Japanese companies will strive at every turn to create a captive market, hoping that once you've set foot in their little quagmire you will stay stuck with them.
If you ever wondered why Canon camera lenses do not work on Nikon cameras and vice versa, why Kenwood microphones do not work with ICOM radios and vice versa, why Sony insisted on Memory Stick over SD card, why Toshiba threw out NAND flash technology, and so on then this is why. Try naming even a single international industrial standard to come out of Japan, you probably can't and I don't blame you. Sharing is not in Japan's DNA.
Contrast the US computer industry where our companies besides Apple can and will cooperate to create and utilize common standards and push the market wider and forwards. PCI is a foremost example, but the very foundation of the industry is built on IBM PC-compatibles.
All this means Japan will always be stuck with a bunch of small, individual pies nobody will care about, losing to the rest of the west who cooperate (and nowadays China who force entire industries at gunpoint) for a much bigger pie. You can't win when you're all trying to drag each other down in a zero sum game.