Answer
What is photo metadata used for?
Sorting, searching, mapping, editing and copyright. It exists for good reasons — the privacy problem is a side effect of how well it does its job.
Updated
Metadata is what makes a photo library usable. Your phone builds albums by place and date from it. Photo software filters by lens, aperture and shutter speed. Editing tools read the colour profile so an image looks the same on different screens, and the orientation tag so it appears the right way up without anyone rotating pixels.
It also carries authorship. The IPTC and XMP blocks hold creator, credit, copyright and usage terms, which is how a photograph asserts who made it as it moves between agencies, publishers and stock libraries. Stripping those fields from a working photographer's files removes the machine-readable claim to their own work — one of the few cases where removing metadata is straightforwardly the wrong call.
Newer uses are about provenance rather than description. Content credentials attach a signed record of how an image was made and what was done to it since, which is a response to synthetic images rather than a filing system.
The privacy problem is not a misuse of any of this. Every field doing something useful is also doing something identifying, by the same mechanism: your phone can group photos by place because each one records where you were. There is no version of the feature that offers the convenience without the record.
Which is why the decision is per-file rather than global. Keep what serves you, remove what does not, and see what is actually there before choosing.
More on this: What is EXIF metadata?, Metadata remover.
Terms used here: EXIF, IPTC, XMP, C2PA.