Yeah Lucas isn't terrible about EU... For instance the Boba Fett issue is classic as to exemplifying Lucas's stance on things.
Lucas approved the comics, which brought back Fett explicitly to capitalize on an over-hyped Star Wars background character with no real solid story... Lucas set some "rules" for Fett's character for whoever wrote about him, but he didn't really say anything beyond the few guidelines... Otherwise it was a thing where they could just have at it and put together a story people would enjoy and buy (that last bit being the key).
Lucas himself has gone on record saying Fett's dead to him... In his "Star Wars World", Fett goes in the Sarlacc and starts a long painful death and that's that. No glorious Sarlac vomiting and Fett resurrection.

Now, of course EU fans and Fett fans (most of them anyway) don't agree with that... Even though Lucas himself says it's "how it is" to him, and he is the creator, but that doesn't seem to matter...
That's the fun about any form of outside analysis of art, be it literary or film or whatever... When I had my Tolkien Studies course, one of the key concepts my prof wanted the class to keep in mind was that art is interpreted differently by everyone... That includes Lucas's FILMS even... The established "canon" as it were doesn't necessarilly mean you can't view it differently from different people. The films have different points of view you can develope from watching them... EU's kind of the same. I think Canon is just a GOOD guideline for base arguments/discussions... Like it sets some "facts" for lack of a better term since you're tyring to have solid discussion on a fictional universe...
The EU then is more loose and open to interpretation which makes its conversations sometimes more interesting, while the films are a little more "solid" and "factual" if you will... It's good then because like if someone wants to argue the size of a ship or some such, you can say "no, the film clearly shows it is such and such feet long", and it's tough to debate because "the films are canon" and that's that. Other elements of the films are really easily interpreted differently or viewed with different glasses by different people... Like Luke's growth through the trilogy, or whatnot...
The discussion of the somewhat open-ended EU material though is great to me because there's more personal creative freedom one can use when looking at it. Everything from EU art of a character varies from image to image, and the writing varies greatly too... It's much more condusive to the imaginations of the readers/viewers interpeting it and discussing it as opposed to the films which are more solid and not all elements are easily interpreted in different ways.