David Graeber has suggested that anarchism flourishes in times of peace, while times of war and violent repression produce resistance movements that are themselves violent, militarized, and hierarchical in organization. (Not to mention heavily male-dominated.) That was what happened after World War I, when Soviet communism captured the revolutionary left -- with extremely bad consequences that still persist.
This is why is seems silly to blame OWS for "developing a protest model that fascists could appropriate wholesale." It isn't that the fascists have appropriated it so much as that Western propagandists have used it as cover to muddy the public perception of violent right-wing coups.
On the other hand, protest as a model is generally far less effective now that it was in the 1960s, when it was new and exotic and guaranteed to attract TV coverage. Getting a crowd out in the streets doesn't do much if you're not getting your message across. And armed confrontation with the police can be worse than useless if the police themselves are clueless about the system of repression they're upholding.
The real key to Occupy, I think, is that it was not about protest but about *occupying* -- about moving into the greyed-out wasteland of Western industrial civilization and offering better alternatives. And the potentials of that as a model have only barely been explored.