I think Noel would have been difficult to write for. As portrayed she was every bit Kirk's equal intellect and gumption. She also was (as I gather) able to keep from being overwhelmed by his charms, even though she might have been willing to have a relationship on her own terms. There was an awful lot going on with her and relegating her to a secondary role would have been extremely difficult and giving her more screen time would have meant less for someone else. Too bad, really. That combination of brains, beauty and courage still packs a knockout punch to this day for me!