I think the film is a big experimental joke/critique (a satire, if you will) on Hollywood. I don't want to throw spoilers out in case others still haven't seen it; but there are a couple of points (especially toward the end) where Joel and Ethan get very self-reflexive and comment explicitly on the film. I think you *could* read the rest of the film as such commentary similar genre films, perhaps the genre, and the industry itself.
But that's my generous read ... and I'm a Cohen Brothers fan.
