"Because it is schema less ... you can trivially add new rich schemas" made me lol. Maybe this makes sense to Mongo users, but I have no idea what you mean here and the language you use to describe this feature is, well, contradictory to say the least.
it means a typo in release-15 auto-creates a whole new database without anyone noticing and you sit around and wonder where all of the data went yesterday.
Just today I enjoyed explaining to a developer why his insert into a timestamp failed because of formatting, with a nice english error message. Thanks Postgres!
Whereas the same thing last year with Mongo just inserted the wrong date into a misspelled key and we didn't figure it out for days.
Actually it does seem contradictory reading back on it. I meant it doesn't have a fixed, enforced schema like SQL databases and it is easy to add new data structures e.g. lists, maps, sets.