I dimly recall reading an interview with one of Intel's Sr. Managers on the Itanium project where he explained his thoughts on why Itanium failed. His explanat

I dimly recall reading an interview with one of Intel's Sr. Managers on the Itanium project where he explained his thoughts on why Itanium failed. His explanation centred on the fact that Intel decided early on that Itanium would only ever be an ultra high end niche product and only built devices which Intel could demand very high prices for. This in turn meant that almost no one outside of the few companies who were supporting Itanium development and certainly not most of the people who were working on other compilers and similar developer tools at the time, had any interest in working on Itanium because they simply could not justify the expense of obtaining the hardware. So all the organic open source activity that goes on for all the other platforms which are easily obtainable by pedestrian users simply did not go on for Itanium. Intel did not plan on that up front (though in hindsight it seemed obvious) and by the time that was widely recognised within the management team no one was willing to devote the sort of scale of resources that were required for serious development of developer tools on a floundering project.