The main question is what behavior is being introduced. I haven't researched deeply, but apparently the add-on does nothing until the user opts-in on studies.
Yeah, add-ons from Mozilla merits the same trust as the browser. But this cuts both ways, this stuff undermines my and probably more people's trust in the browser.
IIRC the person that advocated for Chromium (instead of a third-party Firefox rebuild) base it on performance (they were dubious Quantum is actually better, I personally find it fast enough except when loading Facebook), as well as the alternative versions of Firefox not keeping up with the official version. Also, supposedly Chromium (as opposed to Chrome) settings are reasonably privacy-friendly out of the box.
They did recommend installing uBO-Extra in addition to uBlock Origin on top of Chromium, which is revealing -- with Firefox, there is not even a need for uBO-Extra.
My original point (which I didn't elucidate clearly enough) is that this Looking Glass experiment is resulting in unwarranted backlash against Mozilla -- whereas from the standpoint of preserving an open web and protecting user privacy it's actually one of the better players.