You know why I
like Trek's canon policy? It includes more
than three movies' worth of live-action space adventure that doesn't suck!
But Star Wars consists of 6 movies, a crappy holiday special some possibly related movies with Ewoks, 2 animated films with the droids, and animated micro-series, 1 CGI movie, 4 and soon to be 5 seasons of a TV show, and another animated show currently in production.
And no your opinion of any of those does not affect the canon status of any of that AT ALL. (I really wish fans would get that canon isn't a personal opinion unless you actually own the show in question and even then they can change their mind.)
besides not everyone reads the books hence why making anything live action adhere to them is madness.
Yes. Star Wars needs its expanded universe to flesh out the details, because actually not a lot is given, in the movies. The films are a tiny snapshot in time in the SW universe.
ST canon policy dictates that only on screen materials are canon. Which is fair enough, as Trek has over 700 episodes spread over six television series (counting TAS) and 11, soon to be 12, movies.
SW has six movies, two spin off Ewok movies, an Ewoks cartoon, a holiday special, a droids cartoon, a Clone Wars miniseries, a CGI Clone Wars series, a CGI Clone Wars movie, an animated spoof series (Detours), and a possible live action series in the making.
And that's before we even get to the countless books, video games, comics, etc in both franchises.
I haven't read a lot of the SW books. Or the ST ones, for that matter. More into visual materials based on these franchises.
Personal opinion doesn't make something non canon. if it was produced, filmed and aired, it's canon. Even Caravan of Courage.