Well, I disagree with you about the non-camp quality of the 1978 Ralph Bakshi Lord of the Rings, but even if that were true, are you saying that changes the track record of SF and fantasy movies in that period?
The Bakshi movie definitely isn’t camp. It plays itself way too straight (so to speak). If it reads as corny today it’s because it’s such pure, guileless 70s kitsch.
Also, I realized rewatching it recently for the first time in forever that the Lemmiwinks episode of South Park is an homage to the Bakshi movie!