Because it’s possible to query a structure field on other fields such as the select field. It would be nice to have unique id’s so a relation would stay intact when the structure field data changes.
It’s possible to create a field plugin that creates a uuid and then add that to the structure field its fields. This works when the user adds a new entry. But won’t work when an entry is duplicated.
Same feature with https://kirby.nolt.io/166
Yep this id would automaticaly be the unique key you mention in 166.