The aforementioned by others creation of a new file of any kind (which I wouldn’t consider a rare and exotic use). E.g. a new document or text note. Sure, it can just get some predefined name like “Text_Note_2022-07-04.txt”, but in most cases the user will then need to instantly go and manually change it in some file manager to something meaningful, or else in a few days he won’t remember which note is which.
But also downloading of files, as they often have names that one would like to change to something more meaningful. Why not allow to change the name upon downloading, rather than having to do it manually and requiring a file manager for that?
What if it is about downloading a file via application, not the browser?
The application I am currently working on downloads an audio file, but not directly to disk but to a memory buffer (as QByteArray), from where the user can instantly preview (pre-listen? ) it, decide if he wants it or not (and make some modifications) and only then save it. Again, no possibility to let him choose the name, whereas those files by default often have pretty meaningless names.
As I said, it is not that I am trying to invent something exotic. File saving mode (where the pickers ask for file name) have been present on other platforms. For example, on BlackBerry 10, file pickers had a “mode” property of which one of the options was FilePickerMode.Saver or FilePickerMode.SaverMultiple. In such case, it was asking for file names (including the possibility to display some predefined name and letting the user modify or accept it). So, SFOS file pickers are definitely a STEP BACKWARD in this regard.