Josh, I support the idea of doing work to unify logging more in Debian. To the extent that you're looking for the initial consensus to start putting together specific proposals and patches, yeah, doing that per-package analysis and work seems useful.
I'd even support an eventual SHOULD in the real RFC 2119 sense (meaning it's a bug unless you have a reason to do something else), but not in the Debian policy sense (it's a normal priority bug). I think there are some really good reasons not to do this. I really do not want to see web server logs or inn logs in syslogd/journald by default, although I'd support there being a package that does that. Similarly, unless a lot more chroots end up with their own logging (chroots are not containers), I think that dpkg.log being in syslog would be problematic. But I do think we could do better about using syslog/journald and I'd support trying to achieve that.