While I agree that they shouldn't just copy a post-ROTJ story from the EU....and I never really expected them to do that anyway....there IS some really good stuff out there in the EU. Some of this stuff has worked it's way into the films too. For example, Zahn created Coruscant which Lucas then used for Episodes 1-3. Aayla Secura was also an EU creation that Lucas then used in his movies. On the Clone Wars TV Series, Lucas has used characters that were developed through the EU such as Asajj Ventress. There are other characters like Quinlan Vos and Aurra Sing that had extremely minor appearances in the movies but have had a big development in the EU and Lucas used them in the Clone Wars TV series as well. So there is some stuff in the EU that Lucas has incorporated into his work. Therefore, I think labeling the entire EU as second-rate garbage to be tossed aside is incorrect.
I don't think we're going to see a true reboot here at all, other than recasting characters like Luke, Han and Leia (some characters like Chewie, R2 and C3PO can be easily re-used without casting problems). They aren't going to re-do any of the stories from the first 6 movies and they aren't going to change the history that was established in those movies. So I wouldn't compare it to Star Trek or Batman, in that regard. They are doing Episode 7 which is a continuation of the existing stories....not a re-doing of them. While they won't just be copying a storyline from the EU, I wouldn't be surprised at all to see some extremely popular characters from the EU make appearances such as Thrawn and Mara Jade. Frankly, those are such great characters, it would be silly not to incorporate them somehow.
An original storyline, though, makes tremendous sense as one of the things that made Episodes 1-3 so stale is that they were telling a story that we already knew, somewhat. There were many things forced into those movies just to keep in line with that had been mentioned about the past in Episodes 4-6. So there was no real opportunity to get creative with the stories. Just copying an EU storyline would fall into this same trap. I'm pretty excited to see where they take the story and what sort of creative ideas they bring to life....but I'm sure we'll see some incorporation of EU characters, planets, etc. Keep in mind, the head of Disney made it a point to say that Disney was buying the entire SW universe with all of its characters, planets, etc. They are well-aware of the appeal of the EU.
But if they don't want to recast, the big 3's age and shape is a problem.