The current undifferentiated categorization of staff users works fine for smaller blogs and such, although an expanded functionality could be useful for larger publications.
For example, while a publication would have a series of authors that it might want to list on an authors page, it may also have staff, an advisory board, a fellows network, etc., that it might want to split up into separate sections on the same page, or even split up across separate pages.
Although this kind of data would be relatively easy for a developer to hard-code into a theme, making changes (which could occur often) would require repeated theme adjustment, possible only by those-in-the-know. As a result, admins who aren’t skilled with coding would not be able to adjust this info easily, quickly, or even at all.
If Ghost were to add labels functionality to staff users the same way that members have labels functionality, then similar to the way that tags can be singled out and/or omitted with Handlebars, all sorts of different staff users could be singled out and/or omitted in individual pages or across several pages. Theme developers could set up themes with the desired staff user label functionality, while non-coding admins could then easily adjust things via a labels drop-down bar on the pages of individual staff users.
(As a side note, some of these categories of staff users may require extended write-ups, therefore necessitating a way to include more than 200 characters in the bio field.)