Many great ideas begin with the phrase: "Wouldn't the world be better if..." Finish that with, "We freed ourselves of tyranny," and a country is born. "We could unlock the mysteries of man," and you have the Genome Project. However, at the headquarters of Mozilla, I feel like that phrase probably ended up with something like: "We developed an operating system that remedied our moral distresses against successful business models," or "We went after a piece of the pie just like everybody else."
Chrome OS had a similar task. Remove our dependency for local storage and proprietary operating systems and usher us into the cloud. To date, I don't own a Chrome OS device nor do I ever expect to. Most have no need for it. Though the idea is novel, it doesn't work in real life and for primarily one reason: habit.
Mobile technology has had time enough to see its first casualties (RIM) and its first victors (Apple). With Android consuming a majority of the OS market share and Apple/Samsung gobbling up the hardware share, there doesn't seem to be a lot of room for the little guy, the moral competitor. Apple and Google have greatly improved the polish of their interfaces and people are used to them. Coaxing consumers to a new and buggy interface will be nearly impossible. This isn't even considering how difficult it will be to convince regional and national carriers to give it a shot (keep in mind that Apple struggled to find a home for its iPhone, landing at Cingular).
Firefox OS would have been great 3 or 4 years ago. Now, it just joins the ranks of MeeGo, Bada, and WebOS as an alternative in which nobody is interested. If they wanted to make a dent in a world dominated by two companies, they better have a lot more than worn out UI and moral fiber. They would need to blow us away.