Note that is the first ever straightforward announcement of the removal accessible to the end user, and it wasn't even available when release happened (about 12 hours ago). It's like giving a hard hat to a man that has already got to the emergency room.
That seems a bit overdramatic; it's not like people couldn't still access those search engines at all in Firefox; they just would have to go directly to the website instead of using the dropdown menu. I'd imagine that typing the name of one of them into Google or DuckDuckGo would lead to their site pretty easily
In theory, they get it for that reason. In practice, the actual reasons is that if Mozilla went under, Google would potentially have an anti-monopoly case on their hands. Or at least they think it's cheaper to pay Mozilla than to maybe find out if it's the case.
I believe Google knows better than anyone that market dominance is achieved not by “code quality”, or “features”, or “ease of use”, etc., but by attacking the clueless user with ads and press releases, and bundling the browser with crap like Ultimate Super Image Converter 2011, and paying generously for other sources of traffic. (Sorry, Google engineers doing incredible high-tech stuff, you're at most playing the role of exotic animals in the zoo attracting people who then proceed to sad low-tech data swindling.)
It might be less noticeable in the West, where Google hasn't really been challenged, but it was different in Russia. When Yandex had to switch to “defend the user share” mode, it stopped announcing interesting things (it used to please the public with nice stuff here and cool stuff there, and implemented some of that long before Google), and double downed on all that dumb crap (having the browser you fully control, having three ads to install it on a single page, pushing it into everything, and so on).
