Also, slang (widespread at least in Austin, Texas) for a person or idea that is... on the fringe. It's not necessarily wrong and it's not necessarily crazy, but it's offbeat and probably not very well thought-out. Examples include people who become Buddhists in high school after reading Zen and the art of motorcycle maintenance, the belief that God wants us all to love one another because you received a divine message while you were on acid, and thinking that basic daily nutrition involves 5g Vitamin C, 5g shark cartilege, DMSO, and the total avoidance of all legumes due to toxic lectins. People who hold crunchy ideas may be intelligent and highly competent in other fields and other areas of life.

I suspect the phenomenon of crunchy beliefs comes from the crumbling of old, reliable, authoritative knowledge in religion, philosophy, medicine, etc. It's probably also related modern information overload and the proliferation of books that allow people to believe they've mastered a topic when they've really only read one person's views and seen a small part of the field.

I do not know the word's etymology, though it may be related to granola and its connotations, and the general association of hippies with unrefined foods.