People who claim a new movie ruined their childhood are just being over-dramatic, are using it as a shorthand for it destroyed a thing from their childhood, or both.
I do think, though, that sequel can make a story worse pretty easily. For example, the combined story of the Star Wars sequels, prequels, and originals is simply worse than the originals alone. When you just watched the originals, you could imagine your own Clone Wars, they could be whatever cool thing you want. Dropping neat-sounding hints and letting the audience fill in the gaps with whatever cool thing they imagine is a classic storytelling technique get a free feeling of depth. Replacing that cool thing the audience imagined with trade negotiations makes the story worse.
Similarly, character arcs are a thing. The protagonists usually win and end up in a happy place, at least in a non-grimdark universe like Star Wars. Making a sequel that says: Actually Luke Skywalker spent the rest of his life failing and ended up as a miserable old grump makes his story arc worse.
You can just watch the original movies and ignore the rest of course, it is after all fiction so getting the whole story doesn’t really matter. But these are huge releases that get lots of press, and I think it is unrealistic to expect fans to just ignore them.
Maybe I'm making too much of it, perhaps it's just the modern style to use hyperbolic rhetoric in movie reviews.
But for new movies to make old movies worse used to be an uncommon attitude I think. I remember in the 90s and 00s, lots of movies had really shitty sequels, often straight to DVD, but nobody talked about these cash grabs ruining the original movie. For instance Aliens 3, Alien Resurrection and then all the AvP crap... some people like these (I think Aliens 3 is defensible FWIW) but a lot of people really don't. Still, nobody talks about Alien or Aliens (e.g. 1 & 2) being ruined by the later movies. Aliens 3 is frequently criticized for the way it killed well-liked characters from Aliens, but that doesn't stop people from still enjoying Aliens. People just choose to ignore Aliens 3. And why shouldn't they, because Aliens 3 is canon? That's just a legal IP relationship, that doesn't matter.
And Disney has dozens of straight-to-vhs/dvd cashgrab sequels of their classic animated movies, people who don't care for them just ignore them and they aren't said to ruin the originals. There used to be a general understanding that sequels are very rarely good, people were pleasantly surprised when it was otherwise and nobody said their life was ruined by a bad sequel. Because who cares about cannon in animated disney movies?
I've seen Lucas's Clone Wars, but if I watch the original Star Wars I'm not compelled to relate it to the Clone Wars movie. By simply choosing to ignore it because I don't like it, I free myself to imagine my own clone wars.
I think new movies ruining the originals is some relatively recent cultural phenomena that was brought on by internet culture's obsession with canon. The existence of popular sites like wookiepedia both evidence it and drive it. If I'm wrong and it's not an overabundance of respect for IP laws that is the root of this, then why isn't bad fanfic also said to ruin the original?
Of course, it is fiction, so if you want to have your own version of the story and cut off the bad parts, that’s definitely not hurting anyone.
Nowadays studios really lean into the idea of establishing an expanded universe and canon, since then it becomes a recurring revenue stream and all that. So, I wonder if this is an aspect of that trend, just a different way people tell stories and, as a result, consume them.
I think people ignore 90’s disney cash grab sequels mostly because they were so garbage that they didn’t get integrated into the cultural zeitgeist (and also, people who loved Lion King when it came out were too old to care about the sequel).
Stuff like the Star Wars prequels is not quite at that level of badness, might be marketed toward everyone, so it enters the general conversation about the movies. Of course, it is possible to not engage in that stuff, but then, I guess people who are talking about Star Wars in 2023 are interested in the whole thing, right? You can only think about 3 movies for so long, haha. So, I bet lots of people saw them movies, have fond memories, and then moved on, but they aren’t talking about it anymore.
I think some of the reason for the strong reaction is Star Wars is for kids while Aliens is not. There are a lot of people who were in an age of innocence when they watched Star Wars and it gets them upset if the new movies aren't entertaining to them as adults. Even if you did watch Aliens as a kid it's a horror movie in space with a giant bug in the shadows making it a lot less relatable.
I do think, though, that sequel can make a story worse pretty easily. For example, the combined story of the Star Wars sequels, prequels, and originals is simply worse than the originals alone. When you just watched the originals, you could imagine your own Clone Wars, they could be whatever cool thing you want. Dropping neat-sounding hints and letting the audience fill in the gaps with whatever cool thing they imagine is a classic storytelling technique get a free feeling of depth. Replacing that cool thing the audience imagined with trade negotiations makes the story worse.
Similarly, character arcs are a thing. The protagonists usually win and end up in a happy place, at least in a non-grimdark universe like Star Wars. Making a sequel that says: Actually Luke Skywalker spent the rest of his life failing and ended up as a miserable old grump makes his story arc worse.
You can just watch the original movies and ignore the rest of course, it is after all fiction so getting the whole story doesn’t really matter. But these are huge releases that get lots of press, and I think it is unrealistic to expect fans to just ignore them.