I think it's to keep Abrams happy. My understanding is he got "upset" because CBS/Paramount wouldn't stop or pull the original Star Trek stuff from the stores. He felt it caused the fans [new and old] to get confused, etc.
Bottom line, I think it's a money issue. Abrams as well as Disney wants to maximize their money from all things Star Wars. So by "pruning" the branches from the canon, they regain more control over the product.
The first two KOTOR games were fun, as was the Clone Wars TV series.
Wouldn't the Force Unleashed series be part of the EU?
Edited to add link:
»
www.thewrap.com/movies/a ··· ns-91766quote:
How the Battle Over Star Trek Rights Killed J.J. Abrams Grand Ambitions
The franchise's licensing and merchandising rights are split between CBS and Paramount which created headaches for the multihyphenate's production company Bad Robot
A struggle over the U.S.S. Enterprise's past and future helped sour J.J. Abrams on the "Star Trek" franchise and may have contributed to his decision to take on the "Star Wars" universe.