Jadis The Witch
To clarify one instance of why this matters, most routing software, even with quite sophisticated safety options, will consider "highway=residential" and "highway=cycleway" to be of equal weighting and priority for bicycle routing.

This can be manually adjusted if you're technically savvy, but on a 40 mph road like this one, that seems like a safety and accessibility issue to potentially route people off the trail and onto the road.