One of the biggest controversies in the recent history of Star Wars was when Lucasfilm reset the complicated canon hierarchy and labeled the old Expanded Universe as “Legends”. This one event spawned a splinter group of Star Wars fans who have made it their life mission for Lucasfilm to restore the old non-canon “Legends” as the “real” version of Star Wars. Some of these fans think that “canon” is just another word for some kind of evil corporate submission, when that’s really not what it means when it comes to Star Wars.
In reality, canon in Star Wars boils down to whether or not it’s something that a storyteller needs to be aware of.
So that means the Legends stories were never technically canon as anything George Lucas did wouldn’t take them into consideration. Sure, George would take names and things created in Legends (and change them, which is why Coruscant in the movies is pronounced differently), but he never really paid attention to the books.
The Legends stories had absolutely no bearing on the big-screen Star Wars stories George Lucas was telling, which pretty much proved they were never canon. In fact, it was the exact opposite. As George’s movies were supreme canon, the Legends writers had to wait to use certain elements until after those stories were told in the Prequels. That’s why Artoo suddenly had a holo-recording of Anakin choking Padme, some thirty years after Luke met the droid.
That’s why the “new canon” is so exciting. Lucasfilm is actually doing something with Star Wars that no other franchise has attempted. Both Marvel and DC keep their comics continuity and movie continuity separate. With Star Wars, everything is on the same canon level now. There’s no “G-Canon” or “T-Canon” overruling the books and comics. If something is established in a comic and novel, it absolutely has bearing on what can be done with the big screen or television stories.
And we’ve already seen a character introduced in a novel appear in a movie. Snap Wexley was one of the main characters in Star Wars: Aftermath, and he became the “Wedge” of The Force Awakens. We’re also seeing a character George created in The Clone Wars become a major character in Rogue One, and that’s a great argument against some fans who don’t want to regard the animated series as true canon.
Some people disregard the comics and novels due to the past of them not really affecting the greater story. But with the new canon, and how everything established in every medium of Star Wars being part of the larger tapestry, fans who try to pay attention to every outlet of Star Wars will probably get even more out of the movies and Rebels than those who dismiss certain elements of the franchise.