IMO the real reason that Disney doesn't get "real" A-list celebrities for Star Wars weekends is simple, because they don't have to. If people line up for 4 hours before park opening to get an autograph of the guy that played the 23rd stormtrooper from the left, 12th row, in that 3 second scene in the 5th movie, than why would they put out the extra money to get an A-lister?
Personally, I'm very upset at what they deem "celebrities", especially the second weekend, which is when we will be there. Matthew Wood, Lorne Peterson, Tom Kane. Excuse me while I yawn. 2 voice-over guys and a modeler? What, was the guy that combed Chewbacca's suit busy? D-listers at best.