I think you're mostly right. I use it for a few extra things though. Stuff I can think of:

* Timers

* Alerts

* Step counter/fitness tracker

* My fitness app for weight training - I can start a workout on my phone and enter my set/rep/weight counts without needing to pull my phone out

* Phone calls when I'm on walks and do not want to the "full phone" experience, but also cannot be totally disconnected. This paired with Airpods is a pretty nice balance

* Ditto the above but for podcasts/music streaming - especially if wearing workout clothing and I don't have a comfortable place to carry my phone along.

* Basic replies to my "important people" texts - via Siri dictation mostly

* My "RFID" security badge to get into my home/office/etc. using Apple Pay

* Apple Pay

* Quick glance to check the weather w/ a main screen widget

* Quick glance to check calendar

I liken it to having a mini iPhone 4 strapped to my wrist. Useful here and there, and very nice for when I want to get away from my phone or it's too bulky to bring somewhere. Essentially a basic flip-phone for comms, and a connected streaming media player.