It seems to me that the notion of experimentality, of avant-gardishness, is just a defense mechanism against criticism. "It's not bad, it's ART." OK, I suppose you could be challenging the definition of "art" or "song" or "quality", but the road down which those challenges lie - i.e. postmodern relativism -- leads almost exclusively up its own asshole. The perfect expression of any craft -- whether it's musicianship, carpentry, painting, game design, whatever -- comes from creativity within the bounds of the form. Difference without alienation; creativity without abandonment of form; novelty with familiarity. On that front, Of Montreal's experiment fails; their music doesn't sound good.
Some rules you can bend, others you can't. Mastery of a form is knowing which is which.