Pocket can't give carrots to every person on the planet, they can just hope that their carrots appeal to either the majority, or enough to make the production of carrots worth while.
No one is saying that they couldn't have written Janeway as casting off her admiral duties and going to save ______ or using her admiralty to do ________ . And she was not specifically expendable.
Exactly. When Margaret and her writers were plotting the recent arc, I assume they realised they'd be pitching a Starfleet individual with a Borg representative and they considered a shortlist such as Picard as Locutus facing off against a new Borg Queen, Seven vs the Borg, Icheb vs the Borg, Janeway vs the Borg, etc, and if one character was going to be sacrifing everything to save humanity as we know it, that character was decided by the needs of the story, and how the event would continue to propel future stories.
It could easily have been Picard, but then Crusher would be a widow again, once more left to raise a child alone. It could easily have been Seven. Or Icheb. It could just as easily have been Janeway, especially considering her "Endgame" encounter with the Borg Queen.
Brit now says she'd have accepted a not-exploration storyline for Janeway. But would this be the focus of a Voyager Relaunch series? No, it sounds more like a one-off, perhaps a "Mosaic II" and, if it sold well, perhaps more books in that vein. (The first "Mosaic" sold extremely well.) But nothing that has happened so far precludes such a book being published.
The TOS "Crucible" series sold gangbusters, and there was very little outcry from readers that these three novels diverted from accepted recent book continuity. The biggest/only outcry came from Harlan Ellison and his supporters, wanting more money and respect for Harlan.
However, it concerns me (just a little) that Pocket could do a prescriptive not-exploration post-VOY TV series Janeway novel, dealing with Janeway's feelings for Chakotay, but because the author ends up giving Janeway a different hairstyle, or one last fling with Mark, or Janeway switches to drinking tea, or Chakotay gets offered a captaincy that takes him away from his planet-bound beloved, that one of these would be sufficient for
Brit to say, "Nope, not carroty enough."
We can plot out our lives, but fate still plays its hand. I have no problem trusting authors to make what they feel are the best choices for their characters. I don't need a sticker on the cover to say, "This book has a guaranteed happy ending and no regulars die."