I'm a huge fan of Star Wars; always have been. I love the escapist nature of the films, the hope, the action, and yes, even the love in the stories, and that will never change. I was not a big fan of the prequels. They have their place, and always will, but they too are important to Star Wars lore and history. I have not read very many of the Star Wars novelizations, whether they are of the film adaptations or otherwise. That said, I have enjoyed what those have brought to the Star Wars universe as well, as I think the history surrounding the franchise only becomes richer for them.
When Disney bought anything and everything to do with Star Wars (and, FYI, the lot of the 'Indiana Jones' franchise) in its purchase of Lucasfilm, there were several decisions made in order to establish some sort of continuity. As one of those rare individuals who also enjoys 'Star Trek,' I know that in many respects, novelizations of anything other than the movies are not considered part of the canon that is that particular franchise. In that case, I was impressed by director J.J. Abrams' decision to simply reboot the franchise and come up with a whole new timeline during which the newest series of Star Trek films could occur. It allowed the original series to stay intact, honored the literary series that sprang from it, and for the most part, everyone was pretty happy.
To put it bluntly, I've been rather disgusted by the potshots that Star Wars fans are taking at the actors and crew of The Last Jedi. I saw a meme yesterday that had resurfaced comparing why Luke Skywalker vanished to the reasons Obi-Wan Kenobi and Yoda decided to go underground, and this sparked a great deal of discussion during which some issues from the Star Wars literary canon came up.
Being relatively unfamiliar with the Star Wars literary canon—and, as I previously stated, believing that the literary canon was quite separate from the film canon as it seems to be in the Star Trek universe—I decided to do some digging to basically find out if the films and the books were held as separate entities in the Star Wars world.
In short, they don't seem to be, which is fine and I would say is the current cause of much consternation right now. For instance, in the literary world of Star Wars, Ben Solo does not exist as a child of Leia Organa and of Han Solo. According to literary canon, Han and Leia have three kids: Jaina, Jacen and Anakin Solo. These three have gone off to be involved in various adventures of their own, sometimes involving the Force and sometimes not.
Here's the thing that many may not be aware of—at least, I certainly wasn't. According to Screen Rant, the leadership at Lucasfilm—which still exists in spite of the Disney ownership—made the decision to wipe out the literary canon established by the Star Wars expanded universe that had been started back in the late 1980s when a publisher asked for licensing rights for a series of novels set after Episode VI: Return Of The Jedi. That particular canon, apparently, has its own contradictions and issues, so Lucasfilm—and ultimately Disney—decided in order to forge its own path, that particular canon no longer existed as far as Disney was concerned. While there is no ignoring the existence of these books, it was decided that Star Wars after the 2012 purchase of Lucasfilm needed greater continuity, and the expanded universe in its current state did not allow for that.
Further, Lucasfilm has also established a Lucasfilm story group in order to ensure that the current trilogy, the so-called "anthology" films, and any other film or literary creation—apparently also including comic books—has a unified approach. This way, the Lucasfilm Story Group—and Disney as well—can ensure that everything stemming from the original trilogy from the 1970s and 1980s, the prequel series and all other Star Wars works ties up together rather neatly with no significant hiccups in its current rendition of Star Wars canon.
That's the rather lengthy explanation for the sudden existence of Ben Solo and why Jacen, Jaina and Anakin Solo are not a part of this new trilogy. As for complaints about Luke and what happens with him, remember—he had some rather heavy baggage revolving around his father. If you sensed your own nephew was becoming evil, would you really want to be involved in a repeat of what you'd gone through 30 years prior?