The difference here is we're talking about almost 2 decades of books. I've grown attached the narrative, the characters, even the ships in the huge litverse now. It's a testament to all the authors of the stories, some of whom no longer even write Star Trek books, and one or two because they are no longer with us. It's also interesting to note some characters created all those years ago by some other authors, continue to live on the novels today. So it's a long time.
On the other hand, 2 decades is a hell of a successful run. If it comes to an end, we still have something to be proud of.
I'm sure being in the business helped that evolution as well. You see, better than us at least, what goes into making these shows. One thing I do like about Discovery is as King Daniel noted the internal consistency. Unlike Star Trek of the past, they seem to be making an effort to even keeping the tie-ins on track with the show, not only so that the tie-ins don't inadvertently contradict canon, but even the reverse. Now it may happen at some point the show will have to contradict some story element of a novel, but it seems they want to keep that to a minimum.
Didn't the
Short Treks episode about Saru already contradict the books' name for his homeworld? I think their concern with the tie-ins is more about making sure they don't contradict the show the way early tie-ins sometimes do.
You know, I thought Data was always emotionless though. I don't recall a substantial change to him in season 3.
Look at how he reacts to Armus after Tasha Yar's death in "Skin of Evil," and how that gets called back in "The Measure of a Man." Data was meant from the start to have emotions, just in a subdued and underdeveloped way. He was meant to be naive about emotion, not literally incapable of it. You can see that even more clearly in the novels
Survivors and
Metamorphosis by Jean Lorrah, which get into Data's head and show his emotional responses. Those books were entirely consistent with how his character was conceived when they were written. I was really annoyed when "The Ensigns of Command" came along and imposed the hackneyed "robots can't feel" cliche onto Data. (Which is stupid. Emotion is far more basic and simple than sapient thought. It's an inbuilt, automatic reaction to stimuli, just like computer programs are. It should be far easier to give a computer emotion than to give it consciousness.)
Data was largely based on Questor from
The Questor Tapes. In that pilot movie, Questor was initially naive about emotion because much of his programming for it had been erased from the titular tapes, but he still had the potential for it, and at the end he had his full programming restored. Data was also based on
Phase II's Xon, a full Vulcan whose emotions were repressed but who tried to explore and develop his emotional side the better to get along with his human crewmates. Data was originally meant to be on a journey to explore and develop his emotional potential, like those characters.
). 
