It's funny you mention the Hobbit because I've been thinking about this lately.
Before I say anything, I want to admit that I like The Hobbit movies a great deal, but this isn't about that.
I also want to preface this all by saying I'm quoting you because you brought up the Hobbit but none of what follows is aimed at you so feel free to reply if you'd like but also to ignore if you'd like as well.
I should also point out that I have not read the book of The Hobbit in it's entirety, though I've read some of it (probably about the first quarter of it). I'm certain this colors my perspective on the films.
When I first watched Lord of the Rings, hadn't read that book either. But I kind of had been meaning to get around to reading it. When Fellowship came out, I went to see it in the theater.
I thought it was just ok, and not really worthy of the praise it was getting at the time. I had no idea about any changes the movie had or hadn't made to the original story.
When Two Towers came out, I again went to see it in the theater. I thought it was so terrible and ridiculous I almost walked out. Still hadn't read anything Tolkien had ever written at that point.
Didn't even bother watching Return of the King when it came out. I caught bits and pieces of it on cable over the years.
When The Hobbit movies came out I didn't bother seeing those in the theater either. But when I caught them on cable, I thought they were very good. Much better than what I'd seen of Lord of the Rings.
And The Hobbit movies motivated me to go and read Lord of the Rings finally.
And I LOVE the book. It's fantastic. I can see why it's so popular, it's really brilliant.
So since then I've been reading LOTR with my son. And he loved the book as well. We just finished and are following it up by watching the movies.
It's the first time I'm watching the movies since reading the book. I've been excited to watch them because by reading the book it feels like the movies make MUCH more sense. I don't feel like they explain themselves well to someone who has no idea about the story or the characters or background or anything. Honestly I feel the Hobbit did a much better job of that
But here's the thing.
If people don't like the Hobbit it's fine, I don't care about that. It takes Diff'rent Strokes to move the world.
But my sense is that people shit on the Hobbit mostly because it changed the original story a LOT, something you are alluding to in your post.
But my sense is also that people praise The Lord of the Rings in general, and I noticed you didn't mention it here, while ignoring that the films changed a tremendous amount from the books, and most of the changes are really bad.
Now that I'm watching the films for the first time since I've read the book...
FUCK.
I get some of the changes like leaving out Tom Bombadil or the barrow wight or replacing Glorfindel with Arwen. I don't like it, but fine. I get that even with 4 hour movies you have to make some time concessions.
But some of the other changes, and one in particular especially, are nearly unforgivable.
The elves's involvement in the goings on and most egregiously some of the fighting is major and changes the whole tenor of the story. (Part of the whole point in the book was that the time of Elves was dying away and the age of man was dawning.)
Aragorn falling off of a cliff was pretty dumb.
Faramir being tempted by the ring and attempting to bring Frodo and Sam to Minas Tirith was really bad. That changes a lot about Faramir's character. Yes he had a change of heart but it was a big deal in the story that he was in contrast to Boromir.
And by far the biggest change for the worst is Frodo siding with Gollum and telling Sam to go home, going on without him.
That was so far out of character for both Sam and Frodo it changes the complexion of everything. Frodo never would have done that. And Sam never would have listened. For God sake Sam almost drowned before letting Frodo get away from him.
Peter Jackson just pisses on their relationship here, and shits on the audience for good measure.
And there are so many more shitty changes as well.
Which brings me to my point, and what I've been wondering lately since rewatching the LOTR movies.
Why do so many people shit all over the Hobbit about all the changes it made to the story, but far less people take umbrage with Lord of the Rings (and indeed it's frequently lauded) despite many egregious changes?
It honestly baffles me, because while I admittedly haven't read most of the Hobbit, I can't imagine the changes there are any worse than the worst of the LOTR changes.
So why are they regarded differently?
All that said, I am enjoying the LOTR movies now.