Daniel Johnston: What am I missing?

I'm not a stupid man, nor am I a philistine. I don't have to like a work of art to "get'' it. It's the same way with popular music. I don't listen to Nirvana, for example, but when my kids brought the band's music home, I understood just what Cobain's wail in "Smells Like Teen Spirit'' was all about: the anger, self-pity, ennui and disaffection of a whole generation.
Personally, I think CCR did it better, but who am I to judge?
But I watched a documentary this week about a manic-depressive musician named Daniel Johnston who has a pretty elite cult, judging from some of the people who have covered his songs.
The guy is as crazy as a bedbug, but then so was Van Gogh.
But I've listened to his work, and I just go "Huh?" The music is muddled and the lyrics never rise above the level of a precocious junior-high student.
Any Daniel Johnston fans out there want to clue me in?