You can go from east to west coast in the US in 10 days while limiting yourself to ~210 miles per day. For a retired person with little need to hurry that's reasonable even with only nightly charging.
Personally, I have little interest in driving 600+ miles per day making fast charging minimally useful.
The big long range use cases in California is San Jose-Tahoe (with its mountain climb reducing range), LA-SF, LA-NV & SF-SD. So you would want a supercharger for those trips.
Also for car commuting in big metros, 40-60 mile one ways are common enough, which is 120mi round trip. The previous generation of affordable EVs had 80 mi ranges, which didn't work for those metros.
~8 hours charging at work is a plenty to top off after a 60 mile trip. However, 80 mile EV's are not designed for people with long commutes. I live 4 miles from work and their are charging stations in the office parking lot. So, based on my habits an 80 mile EV would cover 99% of my driving just fine.
However, I still think ~300 miles as the practical minimum because I do take longer trips and know I would occasionally forget to charge sometimes.
A lot of people don't have charging at work, so they have to charge at home. Or they might want to visit a friend that is 40 miles away who also doesn't have a charger.
What coastal cities are 2100 miles away? Maybe for few that are retired, but 210 isn't the best for trips that far, and that's assuming the chargers are exactly at where you need them to be
Personally, I have little interest in driving 600+ miles per day making fast charging minimally useful.