As a Star Wars Literature fan, it's sad to see all the books I've read over the years go down the drain. I think it would have made logical sense for the new series of movies to pick up after Star Wars Crucible and go from there. Still though, through the course of the EU, we have lost a lot of characters that are pretty essential to Star Wars plots after episode six.
First off, 2 of 3 Solo children are already dead. In the books, they make references to Anakin's demise and discuss Jacen's fate almost constantly. In a film where those characters have never been introduced onscreen, these names mean little to nothing to the average movie goer, and their deaths, and how it effects others, would be lost.
Second, Luke has a son, but no wife. Now, I know it wouldn't take too much to explain away the absence of Mara Jade, but time is everything in a two hour movie. The emotions that Luke has for his dead wife would again have no meaning to most viewers.
I've heard the new Star Wars movies been equated to how the marvel universe has been handled, with similar characters and plot lines from the source material. I think is sounds like a great idea, considering how well done I think the marvel movies are. It will give us a chance to see characters from the EU in the films that we never would have seen if they hadn't gone this direction.
Now, what I wouldn't appreciate would be if they invented new characters to fill the slots of Leia and Hans kid's or Luke's wife. I hope Disney realizes that sequels work best when they have a good blend of both familiar and new.