It would be nice to be able to edit the attributes of a feature service and still be able to add related records, without having to make the geometry editable also.
Ongoing field inspection of assets via a collector app.
Edit an attribute of a hosted feature service in AGOL to indicate some status change, WITHOUT geometry becoming active for edits.
Add a related record to a table describing inspection parameters. Thus allowing reports to be run on asset inspection history.
This is a similar idea to the The Hydrant Maintenance Inspection solution just with the added ability to change hydrant colors (for example) via the collector app.