alt Hacker NewsIts not just that each new "feature" is unnecessarily difficult to disable, and already active-with-privacy-side-effect by the time you notice.
Most new "features" are by now covered by an existing setting and/or policy. Yet I recognize a pattern of introducing new "but did you opt out of THIS NEW thing?" or "but did you opt out of VERSION TWO of this previously rejected thing?" setting/policy. It has become unsafe to upgrade to new Firefox releases, because each one will disrespect previous user choice in another unexpected way.
If you don't want new features, don't upgrade it, what in the non-sequitur is this? I get the argument that it SHOULD be OPT-IN rather than OPT-OUT, but that would require annoying pop-ups every upgrade that explains the new features and ask if you want to OPT-IN. That is more burden on the developers and will annoy more users than benefit.
If you are concerned, they do have what is called a 'changelog' that will explain all of the new features and how to switch them off if you like.