Star Wars, however, has always been one universe and the books have always been canon.
No, they haven't. That's the fiction Lucasfilm tried to sell fans, but it was never true. There have been plenty of times when tie-ins have been contradicted by later movies or other tie-ins. The early Marvel comics in the late '70s once had a flashback in which Darth Vader and Luke's father were portrayed as two separate people. The first novel,
Splinter of the Mind's Eye, contains a number of elements that were contradicted or rendered problematical by later movies, such as a direct confrontation between Luke and Vader and fairly strong romantic content between Luke and Leia. The prequel movies contradicted a bunch of stuff from earlier novels and comics, such as Boba Fett's backstory. The animated series
The Clone Wars ignored Karen Traviss's Mandalorian novels. The tie-ins have been getting overwritten by the source material all along, because that's how it always works. It's just that the novels have struggled to come up with
retcons to patch the inevitable plot holes, and a lot of their content has just been ignored or rationalized away.
They're taking the same storyline that has always been canon, and after readers have spent their money on it for 2 decades, they are now saying it's not canon. I don't agree with that.
Because it never
was canon. This, again, is hardly the first time something in the Expanded Universe has been contradicted by the films. It's just that, before, the EU retconned itself and
pretended that there hadn't been a contradiction, but there have always been parts of it that have been cast aside in favor of new screen canon. The only difference here is that it's the whole thing instead of bits and pieces.
I just don't see why the EU has to be dumped.
Because most of the people who see the movies will have no idea it even exists. Because it's a subsidiary, supporting component of the franchise catering to a finite segment of the audience. Because the movies make Disney immensely more money than the books do so it would be stupid for them to inhibit their choices about the movies based on something in some old book. Because tie-ins are not canonical, and Lucasfilm abused the word and misled its readers by claiming that they were. Canon, by definition, is the original work itself. Anything supplementary to that from another source is, by definition, not canonical. It merely supports canon, and can strive to coexist with canon and stay consistent with it, but it will never
direct canon, except to the extent that canon may find it useful to borrow from it. And if it gets in the way of canon, then it gives way, because it only exists to support canon.