That couldn't be a less accurate description of Firefox OS.
aimed solely at content consumers: No. FxOS phones can't do as much as a Nexus 4 or iPhone, but they aren't meant to compete with those. Mozilla's targeting emerging markets where most people don't have smartphones or maybe even computers at all. At $80 unsubsidized, the ZTE Open is approaching feature-phone price and it can do a lot more than a feature phone (and will do more still once FxOS matures).
neutered only to run web browsers: It has full-fledged apps. Using web technology under the hood isn't the same as running in a browser.
NIH development environments: You can't get much less NIH than adopting the web itself, which everyone already uses and develops for, as your platform. If you look in the Firefox Marketplace, many of the apps you see now are web apps, written without FxOS in mind at all, with maybe 15-45 minutes of effort to package them for the marketplace.
tied down to specific languages: There are hundreds of languages that compile to JavaScript[1], and some, like ClojureScript, are already seeing real-world use in commercial apps[2]. With Emscripten, you can use any language that compiles to native. There are performance and debugging challenges but they're getting addressed with efforts like Asm.js and source maps. In 2013 you don't have to write JavaScript to use the web as a platform.
aimed solely at content consumers: No. FxOS phones can't do as much as a Nexus 4 or iPhone, but they aren't meant to compete with those. Mozilla's targeting emerging markets where most people don't have smartphones or maybe even computers at all. At $80 unsubsidized, the ZTE Open is approaching feature-phone price and it can do a lot more than a feature phone (and will do more still once FxOS matures).
neutered only to run web browsers: It has full-fledged apps. Using web technology under the hood isn't the same as running in a browser.
NIH development environments: You can't get much less NIH than adopting the web itself, which everyone already uses and develops for, as your platform. If you look in the Firefox Marketplace, many of the apps you see now are web apps, written without FxOS in mind at all, with maybe 15-45 minutes of effort to package them for the marketplace.
tied down to specific languages: There are hundreds of languages that compile to JavaScript[1], and some, like ClojureScript, are already seeing real-world use in commercial apps[2]. With Emscripten, you can use any language that compiles to native. There are performance and debugging challenges but they're getting addressed with efforts like Asm.js and source maps. In 2013 you don't have to write JavaScript to use the web as a platform.
1. https://github.com/jashkenas/coffee-script/wiki/List-of-lang...
2. http://keminglabs.com/blog/angular-cljs-weather-app/