My opinion, the species and water conditions contributed to this being a feed versus an exploratory bite like you're describing. Also, if this shark had attacked humans previously as is being speculated, that could contribute, too. Sad situation. There was an attack some years ago by a white shark off the coast of southern California and the victim was consumed in that case, too. Don't know of any others in recent history where the victim was mostly or entirely eaten.
People think I'm an idiot or something, because all I do is cut lawns for a living.