It isn't like Lebron doesn't take clutch shots. He takes plenty. Percentages exist for a reason. early in his career he didn't seem nearly as clutch or as ruthless, but that has changed. Especially this year... While your one-shot thing might be right, if I had to take one player to get me points on a possession, it would be LBJ over Kobe every day of the week.
Not trying to knock Kemba, but when he is leading a team of scrubs to the lead in the finals, he can be as inefficient as he wants. Remember, people knocked James' efficiency plenty in past playoffs (most notably in his first finals appearance). Winning is what matters.