Because it's fun to. And for sentimentality's sake. And because they can be enjoyable on their own terms.I just find it an immature reaction to something one doesn't like. Similar to a child sticking its fingers in its ears and shouting "lalalalalala" when faced with a statement they dont like. I also find it intellectually lazy. Being a "creative" type I prefer solutions that do not include the dustbin.
So, I'm not inclined to disregard: Voyager, "Spocks Brain" and Star Trek V no matter how much they disappoint me. I'll work as hard as I can to make them "fit". If I was a writer and could spin a bit of continuity from them to create a story I'd do so with relish.
But I hear you say you're being creative while others are being lazy and childish. You conjure increasingly improbable rationalizations rather than factor for disparate real-world production teams and philosophies. Other fans artfully create alternate histories and parallel dimensions for their entertainment. An argument can be easily made for the reverse of what you say.
I don't think you and I or other fans who do what we're talking about here are all that different. I too think up rationalizations to make everything fit. And I wonder if there's anything on TV or elsewhere that you simply prefer to ignore. I think it's human to do both and that everyone does.
No, as you defined them for us earlier, they're two different things.Canon is "big picture" and continuity is the details. "WNMHGB" is canon, "James R Kirk" was continuity.
Same deal. You don't need to ignore an entire movie or episode to ignore an aspect of it. Writers build new stories from aspects of earlier episodes while ignoring others all the time.I see a difference. In one your simply altering the ending of a movie. You're not pretending the entire movie did not exist because it didn't fit your vision of the Rick/Ilse relationship.
It's give and take. No one pays a writer to write a show no one else likes.Ratings matter because of revenue. Any changes based on ratings are reactive and not always creative.
Also, one of the reasons rating or test groups or opinion polls matter to writers is because they can be sources of constructive feedback. If a writer didn't need that, there wouldn't be any editors.
I keep having to remind myself of the types of fans I've run across on these boards that fit this description to keep from taking it personally.Also "lalalalala" is not the best way to critique and express displeasure.
Its the third solution: "Nope never happened" that I avoid. That seems to be a bigger cheat than any "increasingly improbable rationalization" someone comes up with. At least with the latter an effort is being made. There's no art in saying "Show/Movie X is not canon." Thats what I find childish and lazy. If they are creating a different continuity to fill in that spot, then they are being creative. Fan created Alternate histories and parallel dimensions are fun. But lets not fool ourselves in thinking it "matters". Though I am reminded of a story told by a comics pro who had this fan constantly haranguing him over "errors" in the series he was writing. Turns the reason the guy was so upset was that the pro's work was contradicting the fan's fanfic. 
. Rationalising much?