Seriously what was the reason for this ban on the reuse of original characters?
Richard Arnold felt that original characters took the focus away from the regular characters.
I heard that another TOS novel, Uhura's Song which had another well loved original character (Evan Wilson, AKA Tail-Kinker to Ennien) was supposed to get a sequel as well. But it didn't get published either. Was that during Richard Arnold's time or was there something else going on? I read this on Wikipedia, so it might not be accurate.
I don't know if there was ever a sequel to Uhura's Song planned. Thinking about the book (which I last read about twenty-five years ago), I can certainly think of what a sequel might cover -- Kirk and company getting to the bottom of the mystery of Evan Wilson and discovering who she is. But, personally, I feel that she's more interesting because of the mystery of her identity. The answers might not be as creaas what each reader believes.