In between, the whole cycleway thing happened, still going on, very much like the newer sidewalk/footway phenomenon.
Key difference:
Foot traffic by default can cross the road anywhere. Cycle traffic in many places needs a designated or allowed crossing (or dismount); in many other places bicycles can cross anywhere, just like pedestrians.
Essentially, as long as the mapping reflects reality and provides the information, this is a data user’s problem, but IMO we should to be pragmatical about usability of the information.
If pedestrians can cross the road anywhere and there are no clear and sufficient designated/allowed crossing places, I prefer tagging sidewalks/foot lanes on the way representing the main road.
If the sidewalk is physically separated and crossing anywhere is clearly not intended, and there are designated/allowed crossing places, it’s fine to map them as separate ways, at the discretion of the mapper (or community consensus, I’m told it still exists).
Nonetheless, if I imagine being a data user for routing/navigation, seeing this development in ever-increasing micromapping, I would have to consider how to avoid unnecessary detours where simply crossing the road is possible and allowed. It’s not very easy, I think, but there are many clever people out there. Usually, if I think of something, someone somewhere has already solved it.