It did. Lucas and Lucasfilm outlined a ton of rules for what the stories could and could not do. Fast forward to The New Jedi Order undertaking and you get Lucas, Lucasfilm and publishers all involved again in this huge conversation about what can and can't happen.
A dozen authors simultaneously writing 19 books from different views spanning years in the universe, including the same cast in all of them. They killed Chewbacca and to a lesser extent, they killed a ton of characters that had been written around for decades. They brought a new way of looking at the Force, they showed us how stupidly bad ass Luke Skywalker was and gave us Leia as a Jedi. It was huge. It was awesome.
Then we get GL saying in one of his interviews he never gave a damn and it was all(the EU) basically an alternate universe. The man who contradicts himself more in single interviews and videos more than most people do in their entire lives, and on this subject? Mr. "I wrote a trilogy, no wait I wrote 6 movies, no wait I wrote 9 movies, no wait again, Disney I wrote you a new trilogy!" Suddenly everyone wants to take his word as law? Even some of the same people who wanted to stake him up because of the prequels? Yeah, K.
Along comes Disney, and they throw the baby out with the bathwater.
If nothing else, nearly 40 years of technology writing was the biggest loss in my opinion:
Suddenly everything about lightsabers is bland and boring.
They give capital ship a gas tank.
TIEs and X-Wings are manufactured by the same company.
They're building Star Destroyers......on the ground?
The list goes on and on.
Not all of the writing was great, but damn if there weren't a ton of great characters, places and events during that time. Not to mention expanding on the Force in some crazy ways.
The dismissive way people treat the EU/Legends is kind of ridiculous.
Kind of like how so many talk trash on (or downright hate?) Boba Fett yet at the same time don't accept he's the sole reason y'all got Jango and the Mandalorians expanded upon.