I still can't stop but think how stretched out the Hobbit films were, for an otherwise short book. That's a sin that stains forever with me. The Lord of the Rings films, do have their own flaws, but they're fairly contained and can be debated as to whether they were good or not. I have so much trouble excusing anything with the Hobbit though.
And I hope we never, ever see anyone tackle The Silmarillion. Simply because, there will be so much improvised fluff in that would-be film, that it'd make the Hobbit films blush.
I think they just shouldn't have made it in fhe first place as it clearly wouldn't work as a show. Instead they just made everything up and used all the nouns. There are clearly some stories that can be adapted and some that cant and I hate the trend of just adapting things with big names attached to them to make money. Dune made for cool movies, Rendevous With Rama is begging to be adapted to the screen and I can't wait for it. Asimov is dialogue driven and concept heavy and just shouldn't be adapted.
(edit: stop adapting everything and just make up new stuff i.e. give me raised by wolves back you fucks!)