Usable addition, and the fact that it is only in-browser is actually a merit in some cases. Firefox gets a lot of hate but is way more privacy centric out of the box compared to Chrome. AI is only opt-in and you can literally customize the entire browser using about:config. Mozilla also maintains the only real competing web engine (not considering Apple’s locked in ecosystem) and they are the reason browsers are open source these days.

AI is only opt-in

Not to take anything away from your overall point, which I completely agree with, but this may be a bit of a stretch. All of the “AI” buttons and features are - to my knowledge - on by default. They have made it a lot easier to change that to “off by default now and in the future”, which is very welcome, but “only opt-in” is, again, a bit of a stretch.

It’s not on by default.

It absolutely, positively is on by default. Moreover, it’s actually quite hard to completely turn off. Even their new fancy switches are sus, but for the longest time you needed to go to about:config and switch like ten different weirdly named parameters to turn everything off.