For real? Fitz and Aguirre are, IMO, two of his more traditional narrative films. There are some that are far more difficult to watch (and I say this as someone who has seen almost everything he ever released). The above mentioned Kaspar Hauser, for example, is more classic Herzog - very slow, with an ill defined plot, and super odd characters who behave in ways that are not really in line with everyday experience.
His docs can only be called docs in the loosest sense of the word. They're always partly made up and partly documentary. It's a style that I think is off putting to a lot of people who believe that documentaries should be more journalistic in nature. In the example you cite, Dieter is shown to be obsessed with doors. This is pure fiction, as I understand it.
Herzog is interested in exploring an alternate side of humanity that isn't always explored in traditional film making, and this is why I think he's an acquired taste. Once you get his shtick, or whatever you want to call it, it's a lot easier to make sense of his movies.