Personally I am pretty new to the Trek fandom. I watched TOS, TNG, and Voyager in the past but it was only till recently that something clicked with TOS. And I have become really into it recently.
Honestly I never thought I would read tie-in novels but here I am with a bunch of them on my kindle. I actually started out reading fanfiction but although I found a few good ones there wasn't much of what I was personally interested in there out there, so I turned to the novels.
Anyways it is interesting for me to read what readers want and what some of the writers want to write. Personally I don't care what era the stories are in as long as it involves the TOS characters. I also don't care about canon which is why I can go back and read the older novels and not care that canon contradicted them.
As far as my interests I just want to spend more time with the characters I have come to love. Good science fiction and world building would of course be a plus but at least for me it is not a requirement as I could turn to other books for those things.
As for character growth and development certainly I like that but I also disagree you can't develop the characters and not change the status quo. Change is not the only way to develop the characters. I think in a lot of ways the Trek characters, while great iconic characters are a bit simplified. They have their specific personality traits and well that's that. I guess I don't understand why an author cannot explore these characters more in depth without necessarily changing who they are at their core. This is also why I asked if there are any books exploring the relationship & friendship of the main 3 in depth (and while some of the suggestions people gave me sounded like they might be good books, I am not sure if anything that was suggested is exactly what I am looking for).
Of course I don't know what constraints writers are under due to canon rules or maybe what I am saying has already been done, so sorry if this post is a bit presumptuous.
I guess I am lucky as a new fan I have a whole bunch of books to explore whereas more seasoned fans have already read them all (although I have no interest to read every ST book).