> don't have a good sense of where/how they are used
This is arguably a main problem with geocodes, however they are well designed or not (I believe plus codes are actually pretty well designed). It is obvious that they can't replace street addresses---unless they don't already exist, in which (uncommon) cases geocodes can actually be a solution---so they have to solve some different problems than street addresses, but those problems are too niche. If they look like solutions looking for problems, that's because they mostly are.
This is arguably a main problem with geocodes, however they are well designed or not (I believe plus codes are actually pretty well designed). It is obvious that they can't replace street addresses---unless they don't already exist, in which (uncommon) cases geocodes can actually be a solution---so they have to solve some different problems than street addresses, but those problems are too niche. If they look like solutions looking for problems, that's because they mostly are.