Does this differentiate between errors and non-errors? Usually journald add some metadata if output goes to stdout vs stderr. I think journald logging is better then our current log files since we do not have log-rotating in place. There are some people that migh rely on some externals tools that parse log files so a release note will be required.
We are using nginx quite a bit but that all goes to the journal. I have just checked a handful of servers and none of them have anything outside the journal.
That being said, I’m a huge fan of the principle of least surprise, and if we are shipping services that by default or in their typical usecases outside of the default write logs directly to disk, we definitely should ship sane defaults for log rotation.
One thing about journald though: it throws away log lines when the throughput is too high. If people want to do accounting on the logs that won’t work, so it should be optional (but maybe on by default)