If I run my application/code v1 right now, I generate data. I expect that if I move to application/code v2, I can leave my data in place and it will automatically apply changes to my data.
I do not get that with postgres. If I am on postgres 16, and I want to upgrade to postgres 17, I want to leave my data folder untouched. When I then start postgres 17, it should just work (tm).
It should also work with code that assumes postgres 16, so I can upgrade my database separate from my application. I can not wait 10 days for a large database to be migrated from 16 to 17 without being able to run it. However, I can wait 10 days before updating my code to support features in 17.
The current upgrade process does not give me such confidence in restoring data and uptime. So I don't upgrade until I really have to.