More specifically, I would argue for the ability to run arbitrarily complex, non-locking, fully-consistent queries against all historic versions of the database, a.k.a. "the database as a value" (also "transaction time" or "system time" temporal queries)
Temporal queries have been part of the SQL standard for a while but are mostly not supported by the major databases. Some databases have partial support or extensions that add some temporal capabilities.
More specifically, I would argue for the ability to run arbitrarily complex, non-locking, fully-consistent queries against all historic versions of the database, a.k.a. "the database as a value" (also "transaction time" or "system time" temporal queries)