Look, I get that programmers are expensive and Mozilla needs to pay the bills somehow,
From my understanding this is about two thing, (1) income diversification, (2) demonstrating that recommended sponsored content can be done without compromising privacy. As the tiles can't run code or track you, and recommendations are all done client side. At least as far as I understand.
but maybe if they just focused on security concerns instead of trying to re-invent the browser every other version they wouldn't need so many programmers?
Give me a break, we also want better performance, process isolation, UI tweaks, new HTML5+ features, new javascript features (ES6), new video codecs (daala), all the stuff that makes web the platform, so we can do more with it...
Did I mention research in VR, yeah, that is crazy, but if Mozilla doesn't participate in the standards development it'll all be proprietary (or hard to implement).