In fact, when you create a new page, you can still edit its name, even if the page is in preview mode.
I have many empty pages, whose names are the the name of the many categories that I used for marking other notes.
Moreover, when you get used to using the hotkey (e.g cmd+e) to toggle preview/edit mode, you will find it is not an issue to change the mode whenever you want.
The following is my observation and opinion:
If you open your notes in multiple editor windows and set each of them in different mode(edit or preview), the new note you created will have the same mode with the note in the activated editor.
So I think this is not a bug.