Star Wars got a bold new start when Disney acquired Lucasfilm and the Star Wars rights back in 2012. However, with the Disney acquisition came a big change: the wide frontier of Star Wars' "Expanded Universe" was officially sidelined. The long line of licensed books, games, and comics that had been dedicated to (literally) expanding the universe and mythology George Lucas envisioned were re-branded with the Star Wars "Legends" banner for all non-canon material. However, Star Wars fans have kept careful note of how Disney's new Star Wars canon still seems to be "borrowing" ideas from old EU concepts.
Star Wars now treats the Expanded Universe pretty much how the Marvel Cinematic Universe treats Marvel Comics. In other words, picking and choosing what they want to use.
Marvel fans tend to love the Marvel Cinematic Universe so much that it never really gets brought up as an issue, but the MCU only selectively chooses the portions of Marvel Comics canon it wants to use, remixing them into new arrangements, or creating entirely new character storyline for the films. However, while it may sometime seem like fans get too caught up with how comics-accurate (or not) big Marvel movies may be, the simple proven fact is that diverting from the source material has not hurt any Marvel Studios movie, at any point. Other franchises don't get such a pass (see: DC).
Disney started blurring the line between Star Wars canon and the Expanded Universe right from the start. When Disney made the big decision between Star Wars canon and non-canon after acquisition, they cut Genndy Tartakovsky's original Clone Wars animated series from the canon. That series introduced the villain General Grievous, who then became an antagonist in the later Star Wars Prequels. Grievous was just the first major Star Wars character to begin in a non-canon project, and make the jump to canon. But he wouldn't be the last.
Grand Admiral Thrawn has just been named-dropped in The Mandalorian, and is pretty much the MVP of Star Wars EU survivors. Thrawn went from being one of the most famous Star Wars villains outside of the films, to suddenly being listed as non-important in Disney's new canon. That got corrected when Dave Filoni and the Star Wars animated team made Thrawn an in-canon villain of the Star Wars Rebels animated series. That show ended on the mystery of Thrawn being lost in deep space - and now The Mandalorian is opening the door for him to be part of the live-action mainstream side of the franchise. The history and mythology of Thrawn within the EU was rich enough for Disney to invest a lot of time and content (including several in-canon novels) to bringing him over.
Similarly, the Star Wars Sequel Trilogy carried many echoes of EU story elements - the most notable being Ben Solo/Kylo Ren. The entire story of Kylo Ren seemed to take elements of the EU's famous story of Skywalker and Solo children. Jacen Solo became Darth Caedus in that mythology, and ultimately had to face his twin sister Jaina Solo in a fatal duel. Jaina also happened to be a perfect mix of Han's technical know-how and Leia's Force sensitivity. Does that sound a lot like Rey, and her story with Ben Solo? Well A lot of EU fans thought so too...
Even The Mandalorian's recent re-introduction of Boba Fett carries brushstrokes of the EU. In that mythology, Fett escaped the Sarlacc Pit and eventually declared himself Mandalorian, even becoming led Mandalore in several wars (including the Second Galactic Civil War), helping to restore the planet's might. It was Boba who trained Jaina Solo to ultimately take down her brother Jacen.
The important takeaway may be this: Star Wars fans have generally enjoyed the elements of the new franchise that were built off the EU. The question is: are the people who put in all the creative effort to make the EU what it is, getting their proper due?
In a previous interview with Comicbook.com, Clone Wars, Rebels, and The Mandalorian creator Dave Filoni gave his own ode to the EU and its creators:2comments
"I think what you see in a lot of the work that I get to be involved with is that I have a tremendous respect for all the people that worked through that era," Filoni told ComicBook.com in an extended conversation about the Expanded Universe. "I felt like those storytellers were really able to keep Star Wars alive and very vivid for a bunch of people, myself included. I don't think you can ever take anything away from that effort. I would never frankly, personally, try to marginalize it. A lot of it is very good. I didn't read everything. I don't know it in detail as some of the fans do, and so that's why I would hesitate to say that I'm this mega EU fan. I just have a tremendous respect for it all, and I have a tremendous respect for the fact that people love it. I knew, many of us did inside Lucasfilm, how difficult it would be when we're saying, 'Okay, these are now Legends regardless of how much that makes sense.'"
Marvel and Star Wars are both going strong right now. Disney just recently revealed even bigger things to come from both franchises.