I think you've hit the nail on the head with that, sf. My standards for film - particularly for films of my favorite books - are very high. For these films, I thought that nothing short of film masterpieces ala Lawrence of Arabia were warranted. This is exacerbated by the fact that I am aware of many great directors that I believe could have made a much better adaptation, and much better films. It's this opportunity lost that frustrates me.Perhaps the difference between our views is that I am more than willing to "settle" at this point in my life and be very thankful for what I get rather than perfection which I no longer expect from anything.
But what leavens this frustration for me is that there are some scenes "shot through" PJ's canvas, which are wonderful and sometimes sublime. The FOTR prologue, the early scenes of Gandalf's cart shambling through the Shire, the reveal of Dwarrowdelf, Boromir's death, Frodo and Sam looking out over the Emyn Muil, Gandalf and the Balrog's plunge into the depths of Moria with that exquisite long shot of the deep lake, the Rohirrim on the plain, Éomer's confrontation with the three hunters, the glorious image of Meduseld, Theodred's funeral (my absolute favorite), Théoden lamenting at Theodred's grave as the sun begins to set, Gollum's end-of-TTT monologue, the lighting of the beacons (perfect), Gandalf riding out onto the Pelennor to drive away the Nazgûl with a shaft of white light (my single favorite shot across all three films), the eerily august glow as the forces of Mordor make their way into the outer rings of Minas Tirith killing as they go, the elemental beauty of Frodo and Sam on the slopes of Mt. Doom as a rain of fire descends in the background, the look on the faces of the fellowship as they realize Sauron has fallen, but also that Frodo and Sam have likely been sacrificed, the sublime flight of the eagles, the perfect "good morning" scene, Thranduil on a massive elk (love that touch), Bilbo's hilarious overly-polite attempts at managing the dwarves, the Battle of Azanulbizar (possibly my favorite "battle" across all four films), and again, the eagle rescue, with that gorgeous long shot of them flying over the hills, and finally, that wonderful lingering shot of the thrush flying toward the mountain, and then tapping snails against the rock.
These are all great moments, and some of them are my favorite moments in cinema. So I am grateful for that.
But because they are overwhelmed by so much other stuff that I dislike, it is hard for me to watch the films again and again, as I read the books again and again. Essentially, I do a lot of fast-forwarding!
In any event, to perhaps ironically quote Faramir in Osgiliath, "I think at last we understand each other."
This is really what it's all about. I love the books, and I love film, and I have perhaps impossibly high standards for what a film of those books should be. Not everyone carries that ridiculous burden!
Best,
PtB
Perhaps it needs to be moved. . . .
IMO Spirited Away is the only Ghibli movie that can stand next to Pixar's parade of masterpieces. But: Spirited Away! 
