There are many Android apps which provide this functionality. It doesn't need to be a part of the system.
We can also treat this as Google not giving much fucks, I think. Not only as "the pure experience". Let's be objective to the both sides of the argument.
IMO though, everything that adds everyday convenience must be a part of the system. Did you forget these phones are sold to people who have trouble tying their shoe laces? All the casual quality of life improving apps MUST STARE THESE PEOPLE IN THE FACE from the get go. They shouldn't jump through hoops.
Maybe you shouldn't look at the Pixels as improved Nexii. Google is aiming for a wider audience now.
The issue you'll run into is that everybody has a different idea of a life improving app. You can't cater to everybody and make their choice the default. Google does a pretty decent job elevating the truly popular apps to the default status: see flashlight, night mode, hotspotting, photo filters, etc. But your life quality app is not my life quality app - and that's ok. That's the place where apps step in.
Maybe things have changed.
Optimizing your life for inferior battery life is absurd.
My former work iPhone could last two days. I'll take that over strange justifications of awful idle battery life, any day.
- Profiles where you can set custom volume, vibrate, and sometimes other settings. e.g. "Home", "Vibrate", "Silent". And easily customise + switch between them.
- Alarms that work when the phone is off. Set your alarm to wake you up, turn your phone off, and the alarm sounds in the morning. Lots of old phones had this feature. My Nokia N9 and Jolla smartphone had it too.