I haven't written on the Dude, but I agree it's a great, hilarious movie. He's sort of a Forrest Gump character, or as you say, a fool. I'll have to take a look at those Beatles lyrics.

The fool is indeed an interesting character in the countercultural context. It's a question of whether a saint might look foolish from the warped mainstream perspective. So some foolishness might be only subjective. It's worth writing about.