It is currently not possible to evaluate all items without labels. Currently, through the use of haslabel like haslabel:en one can see all labels written in specific language.
As a user, I'd like to only add labels to items that don't have any at all.
As a user, I'd like to see the total number of items that do have labels.
As a user, for tools like Extension:WikibaseMediaInfo, I'd like to filter only items within a category without labels.
It seems like a natural extension of the current functionality.