We have a use case where nested items are hard to reorder.
When there is a lot of nested items and when each of them has a long form, manual reordering is almost impossible or at least cumbersome.
The drag/drop is long, you have to move the items up or down through a long list and it’s easy to miss the right drop location.
Possible solution :
move up, move down buttons
move to first, move to last
move bellow an item
move above an item
Or provide a way to close/open all items in a nested collection so that only the drag/drop handle and first property is visible, in that case reordering would be much more usable.
Well, the first is more versatile, but the second is easier to implement, I guess.
I would recommend both since the second is also desirable in order to have a more global view of a long nested collection (we should have a global open/close button for the whole collection).
Personally and for reordering only, the first solution with various buttons is my best.
Note that this feature could fit well with my previous request regarding section separators in order to have more usable and organized UI for content editing.