Umm, I only read through the first 8 pages before posting this, so I may be repeating something obvious..but the point of 4'33 isn't that everything IS music..it's just that anything can be considered music once you place it in the frame. It's just what Duchamp did with his Urinal picture..you wouldn't call a Urinal art, but once you put it in a frame and in an art gallery, what else can you call it? (Bad art, maybe, but it's still art). The same with 4'33..anything that happens during that piece of time becomes music just because it's in a figurative 'frame' in when music should occur.
Essentially, it's only music when you choose to call it so, in which case Cage himself says that 4'33 is not music or is music, depending on how you want to look at it. Of course, the same applies to Bach, and even Rach.
I'll also add that I find Cage's notoriety to be overplayed..I find loads of melody in his work and can find several places I can dance to it.