I think you can view it as a deliberate and calculated insult to all members of a religion (it could be argued that progressive and moderate Muslims would NOT find a drawing of Mohammad offensive) -- OR you could view it as people standing up to threats with defiance. No one has the right to demand or attempt to force others to adhere to the rules of his religion. After all, if hundreds or thousands of people draw Mohammad, continuing to threaten one or two of them makes no sense. I have an idea that that was the initial concept, however poorly conceived it might have been. And I think people feel that their own sense of religious freedom is being threatened. They have a right to respond to that.

Hanlon's Razor suggests I go with the latter explanation, despite the obvious meanness and stupidity of some of the participants.

It's kind of interesting, if you think about it -- the Christian church has had its own, similar, prohibitions against artistic depictions of Christ. It caused a schism that may or may not have been described as Great, as I recall, though it's hard in retrospect to see what was so great about it.

At any rate, I'd caution against equating irreverence with insult, and refusal to kowtow to threats with bigotry.