As was posted on IMDB:
It all comes down to merchandising and streamlining the storytelling. Lucas never supervised the EU; that was Lucus Licensing who let the EU authors do whatever the fudge they wanted, and we, the fans, suffered for it. (Marvel Star Wars comics anyone?) I say let the EU fans whine and company about how the EU is ruined. Good for Disney and Lucas. I consider VII a Post-Jedi reboot that has been needed for almost 20 years.
The tears from their nerd rage will solve all the world's drought problems. So Disney only has to do one thing. "Save the planet, have the next trilogy completely original."