But clarity in the canon, reduced confusion etc, is not a bad thing.
There's nothing to be confused over, because it's really quite simple. The shows and films are the canon, by definition -- the original works by the original creators/owners. The books and comics are not part of the canon, by definition, because they are from outside creators. Tie-ins try to be
consistent with the canon as it exists at the time of publication, to be faithful to the original that they're imitating; but they are just conjectures of what
might have happened between or beyond the canon works. If the canon is history, tie-ins are historical fiction.
As I said, Trek books have been overwritten by new screen continuity many times before, and they inevitably will be again. So any attempt to draw a bright line between what "used to be" consistent and what's "now" consistent is bound to be rendered obsolete in the long run when even the newer stuff starts to be contradicted.
And it doesn't really matter anyways since, as Star Wars just proved with the first episode of The Bad Batch, even when they say the tie-ins are "canon", that's not going to stop them from contradicting them anyways.
Of course, canons are perfectly free to contradict
themselves.
Dallas retconned away a whole season as "just a dream." Marvel Comics constantly rewrites its heroes' origin stories to update them in time. Canon is never a guarantee of consistency, because even a canon is just a story, and if you're pretending, you can always change what you pretend.
I don't think you can count adaptations like movies or TV shows as tie ins, tie-ins have a very specific set of rules and limitations that they have to follow, and have to go through a whole series of approvals. Movies and TV shows are adaptations, and are pretty much free to do whatever the hell they want. We are starting to see the original creators or license holders taking a more hands of role in the adaptations, but even they aren't limiting them the way they tend to with tie-ins.
Yeah, I think that's true. Tie-ins usually pretend to be set in the same reality as the thing they're adapting, to be just more stories in between or after the main ones. Adaptations tell new, distinct versions that aren't meant to be in continuity with the original, that take the ingredients of the original and put them together in a new way to create a new work.
Adaptations that purport to be in continuity with the source material are quite rare. I think the
Watchmen TV series qualifies, as it's meant to be a direct sequel to the comic, though it's out of continuity with the comics sequels that DC did around the same time. The first live-action
Ben 10 TV movie purported to be in continuity with the animated series, but it was later retconned by the series as a parallel universe. I think those come closer to being tie-ins than most adaptations, since they're new stories in the same sequence rather than retellings of pre-existing stories.
And the most popular versions of a thing is always going to take priority. Once the movie or TV shows have drawn a bigger crowd in, they are going to want to give them something recognizable when they check out the other versions. That's why have things like Ian Malcom dying in the Jurassic Park novel, and then being alive in The Lost World novel, or the original white Nick Fury having a black son named Nick Fury Jr. who took over his role in the Marvel comics.
The sequel to the original
Logan's Run novel opened by quickly undoing the ending of the original novel to make the status quo closer to the entirely different ending of the movie, because most of its readers would be more familiar with the movie. Arthur C. Clarke's novel
2010 was a sequel to the movie
2001 rather than the book version (although Clarke almost never had continuity among his different novels or stories anyway).