Yes, but it would also facilitate inaccuracy. The instances of one creator being responsible for EVERYTHING on a book are very, very rare indeed. Giving the ability to populate an entire creator sheet with one name would come in handy for less <.05% of books. When you weigh that convenience against the possible damage that would be done by allowing the ability, it's probably not worth it.
However, I could see some speed advantages in abandoning the drop down nature of creator addition in favor of allowing just two blanks which operate in exactly the same way. One blank would allow the user to type in a creator's name, in exactly the same way we do now. The other would allow the user to type in the job functionality, and it would recognize the position as you started to type the word. You'd only need to type the letter "e", for instance, to enter an editor, rather than pulling something down to the word "editor".
Still it's a niggling kinda thing which might not, in the end, offer such dramatic speed increases to justify the time needed to recode things.