OK, I think a lot of this is definitely people being unreasonable, but it also points to ignorance. Anyone who goes to see the LOTR movies and expects every word of dialogue to be the same as it was in the books is going to be disappointed. Where ignorance comes in here is the failure to realise that a film made in the 1990s cannot and will not be the same text as a novel written in the 1950s. Social change alone will ensure that.
GoT? I never watched it, but I do know that the final season had no published book to be based on. What would have happened if the film-makers for Harry Potter had only had a few notes from JKR to go on to make the last movie? They should have ended GoT when they ran out of completed books.
Star Wars. In the name of sanity, people, this is Space Opera! It’s supposed to look good and sweep you up in the action. It is not supposed to be consistent, logical or have any kind of moral dynamic beyond good guy/bad guy conflict. The pseudo-science and pop-culture philosophy are both there to drive the action along -they don’t have to be consistent, real or even logically valid! Recognise what it is you’re watching.
As to Star Trek, the original series featured exactly three decent episodes. The rest of the time, the only pleasure to be gained was watching a stilted script being abused as Nimoy played Stuffed Owl between the scenery-chewing antics of Shatner and Kelley while Nichelle Nichols looked on with mild incredulity from the back of the set. TNG, DS9 and VOY were far superior in terms of writing and cast (though DS9 was blown out of the ion stream by the incomparable Babylon 5). The cinematic reboot, on the other hand, has decent writing and a passable cast — no wonder hard-core Trekkies hate it!
Regarding the comic adaptations, every character in both the DC and Marvel Universes has been retconned so many times that there is really no such thing as a ‘canon’ version of any of them. Just shut up and pass me the dip, pal, I’m watching this!
The only really revolutionary occurrence in any major fandom has been the introduction of a female Doctor Who, a move which has gained the series more adherents than it has cost it.
But the point remains the same. The so-called ‘fans’ who blow their tops at things that they don’t like are usually the ones who don’t really know or understand what it is that they’re so attached to!