So, in a fairly depressing, but in no way surprising, move, Disney have decided to prune the Star Wars canon down to a manageable size. They decided to clear out the existing 'levels' of canon and revert to a simple "this is canon/that isn't" model.
That's not terribly surprising. Lawrence Kazdan, being a scriptwriter and not necessarily an obsessive Star Wars junkie, isn't au fait with the entirety of the Expanded Universe, so in writing Episode VII, he was sure to trample on a few things. And it's right enought that he should probably be freed up to write the best script he can, without worrying inordinately about minutae of established canon.
But it's also not without its problems.
It appears that this pruning isn't going to take a simple "the movies are in/everything else is out", or even "the movies plus Clone Wars are in/everything else...", but rather they're going to go through the existing EU material and choose based on what's 'good' and what's 'bad'. So it seems likely that Mara Jade, a fan-favourite character from the EU who became Luke Skwalker's wife, will make the cut, while things like the "Dark Empire" graphic novels will be out.
Two problems with this: firstly, those of us who have paid any interest to the EU can't selectively edit our memories. So, not only do we have a bunch of stuff rattling around in our heads that we're not entirely sure we remember, but now we're expected to remember what is and is not included. That's not a 'simplification', it makes things more complex.
Secondly, the EU actually has a pretty strong continuity to it. This means that later material builds on the earlier stuff - "Fate of the Jedi" depends on "Legacy of the Force", which depends on "New Jedi Order", which depends on... If you start knocking bricks out of the Jenga tower that this represents, pretty quickly the whole thing is going to fall apart.
Honestly, a selective pruning is probably the worst thing they can do. Far better to go for a simple in/out approach, based pretty much only on the movies (and maybe Clone Wars). Perhaps take a leaf out of Marvel's book (actually, more DC's book, but that's a nitpick), and label them alternate timelines or alternate universes.
As for whether they should clear out the EU at all...
One of the responses in favour of this move has been that much of the EU material is so very, very bad. And it is. But is "Darksaber" really worse than Greedo firing first? Or "oota groota Solo?", or the "Jedi Rocks" music number in Jabba's palace? "That's so wizard Anni"? Or all the other bits of the films that are likewise so very, very bad? (And before answering, remember also that the EU contains quite a lot of material that is likewise very, very good - see Timothy Zahn's books, the "X-Wing" series, etc. Remove the EU and you lose that, too.)
Here's another issue: the people who would complain most about an inconsistency between Ep7 and the EU are those fans who have obsessively pored over all things Star Wars. They're the people who buy every book, every comic, who make their own Star Wars costumes, who queue for days at the cinema to see the new film on opening night. In short, they are the absolute most dedicated part of the fanbase. Pissing on your most dedicated fans is seldom a good idea (just as WotC about 4e Forgotten Realms!).
The most immediate impact of that is that your fans, having been burned in this way, now have no motivation to buy into your future tie-in materials. Why would they buy the new Star Wars books, comics, etc that you produce knowing both that (a) the quality is ropey as hell, and (b) these are only "the continuing adventures" up until the next time you feel like a cull? Merchandise has always been a huge deal for Star Wars... and now its value is diminished.
(Naturally, I do also have one other reason for not wanting the cull, this one being a little more personal. Most of the foundations of the EU lie in the excellent work done by West End Games for the original Star Wars RPG - to the extent that when Zahn was contracted to write the new Star Wars trilogy way back he was sent those roleplaying books as his research guide. And, amongst other things, that's where the name 'Coruscant' comes from. Being a gamer, I'd rather not see that just getting scrubbed.)
Ultimately, of course, it doesn't matter. Disney are going to do this, and as the owners of the IP they have that right. I just think it's a mistake - in my opinion, the Star Wars galaxy is a bigger, better environment for the Expanded Universe (good and bad) than it is without.
And that's all I have to say on that.