Firefox OS (or more generally, a free phone&OS) is something I do believe is needed but Mozilla had the completely wrong approach towards it. They severely underestimated how much effort is involved. I heard from several mozillians the attitude was "we'll just do everything in HTML5 and gecko will do just fine". (Sounds familiar? It was Jobs' vision for iOS. See how that turned out.)
They didn't understand how much work is involved into making not just a platform, but also an OS (with all the builtin apps, making them not suck is a prerequisite) and the hardware itself. My Flame's only redeeming quality was that the battery died after a week, which kept me from finding out more issues with it.
I don't know that FxOs was ever a solid choice. It was barely ever even a choice. I wish Mozilla would've just funded or partnered with one of several existing players in that space, such as Jolla.
They did. They partnered with Meego (The Intel and Nokia lead platform.). Remember Meego?
Sadly, their ideological mission conflicted with the realities of their target market (and in this case, price-point).
[1] https://developer.mozilla.org/en-US/docs/Archive/Firefox_OS/...
This does need to be close to a 'from the ground up' initiative. And that has nothing to do with latest developer trends.
Firefox OS in its pre-shutdown iteration did not serve these people perfectly yet, but it was well on its way to be a solid choice for them. A choice that held their values first, not just the values of western consumers trimmed to fit.
And now there are no 'open' choices for an open mobile internet device (below 50USD) The cheap knockoff Android phones that dominate that market are preloaded with untrustworthy applications, and ship with unverifiable firmware. The latter is almost never updateable to anything recent or patched for security. This makes for a very exploitative, dangerous web, and it grows more so as it grows more integral to peoples livelihood.
I applaud Mozilla for starting it, but I think the decision to shutter the whole initiative was incredibly damaging. At the very least because now it, falsely, appears to be a cautionary tale to anyone else that may wish to attempt this initiative.