My biggest gripe with Firefox OS was that it just wasn't all that different from Android - both technically and philosophically. Aside of a bunch of selected developer-targeted devices, it was usually being just as locked down as Android was. This was done because of the strategy of partnerships with carriers and vendors, but ultimately it just made it uninteresting for the broader FLOSS community to embrace, as it just boiled down to replacing Java-based stack with Web-based one without making any significant progress in device openness and user freedom. It didn't even help Linux, as B2G was made to use Android-specific layers to ensure compatibility with blobs and unmaintainable vendor-provided kernel trees.