The major flaw in Knol, that I see, is that it has contrary goals. To the extent that Wikipedia does work its success is created by the "wisdom of the crowds" mentality where something is monitored by so many people that bad entries eventually get weeded out. Knol’s attempt to just use "qualified writers" prevents the Wikipedia-esque crowd oversight while at the same time limiting the people who contribute at all. This means less oversight and fewer contributors which is a double wammy.

Related to that Knol is clearly a "me too" project for Google. So while a startup or other focused competitor might see the problems that are hindering the service and rush to correct them Knol’s issues go unaddressed which is why it’s so stagnant now.

At this point, with Google tightening it’s purse strings a little, I expect Knol will be put out to pasture before too long (which sadly will come as a major blow to those fighting the scourge of horniness)