I did say Saavik was the first, didn't I? I wasn't talking about the TMP characters. I don't know if it was audiences or not, but my understanding is that the intention was to phase out the older cast in favor of a younger cast, but for whatever reason, that didn't happen. Every attempt the movie franchise made to introduce a lasting change -- adding new characters, killing off main characters, destroying the ship -- got undone within two movies. Whether it was the audience or the studio heads or the filmmakers, someone decided that nostalgia should win out over change.
Well, you said it was the audiences' want for nostalgia. Perhaps you shouldn't try and pass of your imaging things as fact.