What I'm getting at is that art and consumption of art -- particularly in popular culture -- is not a strictly top-down affair. The artist doesn't dictate the audience's experience of their art. They influence it, sure, but it's a lot more fluid than "Here. This is my art, and you will accept it however I say." And this goes beyond merely liking a particular piece or not.
Storytelling in particular is vulnerable to this because, in my opinion, the art of storytelling is vastly different from purely visual arts (e.g. sculpture, painting, etc.), or other performance arts (e.g. music, dance). There's overlap, but to me storytelling involves a lot more audience participation rather than passive consumption.
Stories are also, in my opinion, far more open to audience contribution and creation. When the storyteller finishes and the audience says "And then what happened?" where the storyteller fails to answer the question, the audience can just as easily fill in the blanks for themselves. It isn't the "official" story, but it's every bit as legitimate in an artistic sense as what the storyteller created. The role of storyteller has simply shifted from one author to another.
I should be clear that this is also COMPLETELY separate from the legal notions of authorship and creation. In that sense, the creator or rights-holder has every right to dictate what is "officially" part of the story's continuity. But bear in mind that authority is derived from law only, and only applies to what may legally be presented to the public, reproduced, etc. (all the exclusive rights granted under copyright law).
Aside from that, the author has no exclusive claim on imagination or creativity. They can tell me "Then, Luke Skywalker opened a bakery where he sold wookiee cookies for many years, until one day he decided to diversify his holdings into inter-system finance, tibanna gas mining, and the import and export of Corellian brandy, all to serve as a legitimate front to his illegal spice dealing activities." But it doesn't mean I have to agree with them.
If you accept the PT, the EU, the video games, the Holiday Special, etc., recognize that this is your choice to do so. No one can force you to accept them; you do that of your own free will. Just because George Lucas or Mickey Mouse says "In the next Star Wars story, Lando Calrissian gets a sex change" doesn't mean you HAVE to accept it and incorporate it into your experience of Star Wars. Ultimately, that's what I'm getting at when I say that I'm the final arbiter on what my experience of Star Wars is. Lucas, The Mouse, or whoever else can tell me whatever they like, but it's up to me what I choose to accept and incorporate.