The same thing happened to the Halo show that happend to the witcher, the writers introduced characters that were there to fill checkboxes without any real substance, they concentrated a lot more on their agenda filled fanfiction rather than the protag, and they made John-117 fight his demons instead of the literal demons around him....
They also hated the "true good Hero vs true evil" story of the games and books, as is a must if you want to become a hollywood writer these days, and twisted the story around enough that humans became the real villains, instead of the "just misunderstood culturally different" poor aliens who just happened to glass a couple of planets and wipe out a couple million humans, no biggie...
Oh and the visuals were all over the place. Some parts did look okay, but other times bare white 3d printed weapons/props were clearly visible in multiple scenes and such nonsense... the money was there, the attention to detail (or the will to give the post production teams enough time) was utterly lacking.
The Hobbit should never have been 3 movies. It should have been a single movie or even better, it should have been the 2 episode (50-70mins each) pilot to a Middle Earth TV show (no, not for amazon's laughably bad soap that we got, that's just absolutely horrible, but something else with Peter Jackson in the lead)
The original isn't even a book, it's basically a short story... Every single creative liberty they took with the writing and characters diminished the value of the original work. Adding meaningless or outright anti-lore characters and their relationships, pointless action scenes that even an 8 year old raised on the worst marvel crap would find cringe, and basically adding no value while wasting all that money and talent... I wish it wouldn't exist in this form.
I do like game-cinematic movies though, when done right. I might give that a watch later. Also, if you like Halo, I highly recommend reading some of the books, like The Fall of Reach (1st of 4 book series, the rest is also great) and Contact Harvest. There's also a bunch of books that follows the enemy, some of those are supposedly good although I never got that far into them.