This has played out in many other markets, including desktops and servers, where higher levels of abstraction won mindshare over time as technology (both hardware and software) advanced to make it feasible. When I started using person computers (8 bit machines), software of any seriousness was written in assembly. The next generation (16 bit machines) brought good C and Pascal compilers, and applications built with those tools. Only now are we seeing serious talk of replacing C/C++ with something else for systems programming (maybe Rust, maybe Go, etc.).
Being right but at the wrong time is just as bad as being wrong. Maybe WebOS was right, but at the wrong time...maybe apps made in JavaScript five years ago weren't snappy enough on a phone. Maybe the tooling wasn't there. Maybe the VMs weren't good enough. Maybe they are, now.
I don't know. But, Mozilla has shown itself capable of taking on the biggest companies in the world with open web technologies, and holding their ground tenaciously. I believe they have the clarity of vision and the technical chops to pull it off.
Finally, I just want a Firefox phone. So, I may have rose-colored glasses. I think Firefox is the bee's knees, and I think Mozilla truly represents one of the most positive forces for good in technology today. I want Firefox OS to win. If it can't win, I want it to be a serious contender.
There are zero switching costs associated with a browser. It costs nothing to download and run Chrome, Firefox, Safari, IE, etc... The switching costs associated with phones is obviously much higher. Mozilla has to win ground in the mobile OS wars before they can even think about defending it.
Not trying to be a downer, I would like a viable mobile OS to break up the current duopoly, especially one that really embraces the web. I just think Mozilla has a hell of a fight ahead of it and it can't win it on merit alone.
Web OS and Windows Phone support for JavaScript are a living proof people don't really want to.