"Network drivers would need to report events like carrier loss, excessive checksum errors, or duplicate MAC addresses. "
these kinds of things are actually available as highly structured (if somewhat underdocumented) rtnetlink(7) messages. i would argue that netlink is a more natural fit for this kind of data.
system logs structured or otherwise need both a degree of persistence (for review and forensics) and immediacy (for booting, lockups, and issues to which one would like to immediately respond). the latter suggests a requirement of display; any infrastructure would thus be at best a strict superset of current logging, and thus add complexity to an area where robustness is a if not the primary concern. of course, it also implies that old techniques can be used as fallback, or prior to initialization...