I think that would be met with more complaints than kudos. "WARNING" is supposed to mean "there's probably something wrong here", and a report of a cascaded drop is not that.
OK, both are good points.
Since the list is truncated and possibly affects objects in other schemas, I would recommend setting
SET log_min_messages = notice;
for that session (for anyone else reading this, no need to set it in the settings file, the above is an sql command).
And then it is possible to view the full list in the log (e.g. after rolling back the transaction with the drop query).