Why aren't trends like these scaring the living hell out of Mozilla, as an organization?
I think they probably do. At least, that's the reason I've always felt explained the Chromification of Firefox. That dumbing-down and relative takeover of the project direction by "UX designers" and "social media engineers" was allowed because the powers at the top felt that it was the only way they could try and recover some of the userbase lost to Chrome.
What they don't realize is that Firefox was created to "take back the web" from the stagnating Internet Explorer 6. It was never about replacing IE as some overbearing dominant beast.
And Firefox succeeded! Development on IE was revitalized by Microsoft, Google released Chrome, and work was renewed on web standards (a whole 'nuther can of worms there, but a separate topic). How did Firefox accomplish this? By being fast, lean, developer-friendly, power-user friendly, absurdly extensible, and with simple and clear design goals.
If Mozilla had simply stuck to these principles, Firefox user share would still have gone down -- it was a certainty due to the additional options for reasonable browsers, mobile usage, Google bundling Chrome with everything they can get their hands on, etc. However, I think it would have gone down less, and maybe even a lot less if they'd remained the browser they were rather than turning into the little puppy following Chrome around.
People who left Firefox for Chrome because they liked Chrome's design better would still have left. But with ChromiFox, people who don't like Chrome are leaving too, because if you're stuck with either Chrome or Chrome Light, you may as well go for the real deal. Sure, there are projects like Ice Weasel and LucidFox which attempt to bring some of that back, but they're relatively niche and don't have the visibility or word-of-mouth needed to take off.
In short: Mozilla abandoned their primary design goals and principles, the same ones that made Firefox great, and the result is user loss, stagnation and, probably, eventual obscurity. As someone who used Firebird, this make me very sad.