My first responst to you would be to ask "Too sympathetically as compared to what?' Shakespeare certainly does not let Iago off the hook for any of his actions. I would argue, in fact, that Shakespeare does not present Iago sympathetically at all. He portrays him quite realistically. The audience gets to watch and particpate with Iago in his master plan to ruin Othello, becoming complicit to his actions. Iago hangs himself with his own plans, and his ambition and arrogance become his downfall. It seems clear that Iago does not believe that his own wife would have the courage or the desire to frame him, but Emilia's devotion to Desdemona and to the truth is what eventually get him caught in the end. But sympathy - I don't think so.