There's some irony that some folks might have gotten hearing loss from headphones in the first place, but it sounds like a useful feature.
The volume limitations only made sense if you never used headphones less sensitive than the oem ones and listened to source audio that was only at maximum volume all the time.
Many people use their phone in spaces where audio wouldn't be well received (and headphones weren't worn). Examples where I'd prefer captions over audio: when I'm commuting, in a loud space, at work, waiting in a doctor's office, anywhere where I don't want to silence all outside sounds with headphones, but would like to watch the video and read what's said.
With song lyrics and audio books, I'd like to hear and read.
Live caption sounds great to me since my wife's family is Russian and I don't speak it very well. We video chat with grandma often and I'm not really involved...
I haven't tried it, but it sounds like this would also be useful if you want to wear headphones to avoid bothering others but you still want to clearly hear what's going on around you.
Live caption on device: Sounds great. Very useful if you are hearing impaired. If you just want captions for the words the are difficult to make out, some AI isn't going to help there. AI's are currently worse than I am at detecting words.
Smart reply: This looks useful. Not having to lose info as you create an appointment or less clicks copying and pasting directions. Yeah, great feature. Good job here.
Sound amplifier: Remember when everyone was up in arms because iPods could boost sound way too loud. (disregarding different source volumes and headphone sensitivity). So everyone limited the power output of their headphone jack. Well, now we've come full circle and we can blast our ear drums the way god intended, it just takes more button presses. This is like yeah, we took away a feature because of hysteria, now it's back.
Edit: Thanks for explaining this to me. This feature does indeed seem useful. Audio that is more clear, being able to hear what's around you, yeah this is great.
Gesture navigation: I hate this. Maybe some people like it. If you are one of those people, I'm happy for you.
Dark theme: I originally though this feature was dumb. Next we'll have gray theme, or blue theme. Battery savings just didn't seem that great. After using this for a while, I like dark theme, in an unexpected way. I find that the black colors are less stimulating and the phone is less of a distraction.
Digital wellbeing: I haven't found these features all that useful. Perhaps someone else makes use of them. I mostly see this as shaming for using the phone too much.
Focus mode: Remember that one android release that made it so you can easily block all notifications from an app. Well, later they made it so you can only easily block a category(can still block all just more presses). Then apps can create as many categories as they want(so you keep getting spammed). This time they didn't do the user friendly release, in order to focus you have to check each app you have installed. Completely backwards like they didn't really want to do this feature.
Family link: I'm not a parent, kids and phones sound like a nightmare to me. I hope this helps you parents. No opinion from me.