The partition concept is very closely related to logical date.  In fact, logical date, and execution date before it, has effectively always been a kind of partition.  And their reason for existing in the way that the do is to support real partition-driven workloads e.g. hive ETL.

Ultimately it would probably make sense to make it so logical date was internally a partition.  Do we need to do this now?  Or can it be done in backward-compatible way in the future?

Can a normal cron dag update asset partitions?

It may seem like an obvious "yes".  But normal cron dags have a logical date, not a partition key, and there isn't an "obvious" way to map a logical date to a partition key.  E.g. should it be a date string? Date plus hour? Month date? Week date?

So the user needs both to opt in and specify the format, unless the dag's schedule is somehow driven by a partition scheme.

One option is to force the user to define a partition scheme.

Another option is to provide an interface to format the logical date as a partition key.

Should logical date be populated when using a timetable in partition mode?

The current answer to this is no.