^ This really nails a lot of the issues with original characters, IMO. For me, that’s where the early DS9 relaunch excelled. We got a great mix of established screen characters and original characters and nobody got left out as the stories progressed. New and unexpected things happened with the established characters, like Ro and Quark’s relationship and Kira’s new conflicts with religious authorities. We also got fully-realized original characters like Shar, Vaughn, and Taran’atar with interesting and compelling story arcs.
Most of all, the authors were given space for this to happen. Since the series was intended to be ongoing, the stories never felt like one-offs, but rather part of a larger whole. When else have we had something like the Mission: Gamma books, with multiple storylines on both the Defiant and the station playing out over the four books. And one of the station storylines was setting up Unity. Since not everything had to be wrapped up in each book, we got to see the development of Shar’s relationships with his bondmates and their conflicts, Ro and Quark trying to sort out their friendship, and Kira slowly coming to realize that something was very wrong with Shakaar. It was clear that the authors and editor were working together to create stories which were plotted in advance, with a clear sense of where the series was going over the next three, five, or more books.
This is what seems to be missing with the current TNG and DS9 books. (I have only read some of Titan and none of the Voyager relaunch or New Frontier, so I can’t speak for those series.) While Chen has gotten a lot of development (partly because it seems several of the writers find her a fun character to use) and, to a lesser extent, Jasminder Choudhury and Sarina Douglas (partly because of their romantic involvements with established screen characters), most of the rest have faded into the background, as you noted. They’re the Lieutenant Kyles and Nurse Ogawas of Treklit.
While I think that many of the current authors work very hard to maintain continuity and characterization across the books, that sense of where the larger story is headed seems to be lacking. With some exceptions – notably DRGIII’s DS9 books and David Mack’s books focused on Bashir – it doesn’t seem like the authors are free to write a book with very many ongoing arcs. The best they can do is what Dayton Ward did in Armageddon’s Arrow – lay out some pieces that they might be able to pick up in a later book. No one seems to be thinking about what’s going to be happening in the book after the book after the book after the book currently being written.
While the reality of the publishing industry may be that editors simply don’t have the time to work with multiple authors on interlocking storylines, or that readers of tie-in literature just don’t buy books with continuing storylines, I still wish that we could see something closer to the early DS9 relaunch in the current books.