Othello really feels like a correction—Shakespeare readjusting his focus—after Hamlet. The mythical, haunted, Danish court is replaced by Venetian Republic businessmen worried about their trade routes. Instead of an introspective, irresolute Prince, the focus is a successful warrior. Othello is anti-Hamlet: all action, decisiveness, impulse. Part of his activity is a poetry that stuns with richness, music and delicacy:
Keep up your bright swords, for the dew will rust ‘em.
But Hamlet’s heir isn’t Othello but Iago. In the scene where Cassio pleads with Desdemona, Iago stands aside and makes his comments. It's outrageous: Hamlet wandered off in order to put on his performances, but Iago stays in the thick of things.
Then in the long pivot scene in Act 3, Iago dupes Othello, creating doubt, then suspicion, then certainty. I don’t think Iago’s being crafty: I think he’s just playing it by ear. It’s not a vision of evil ingenuity, but a vision of gullibility, of jumping to the worst conclusions, of guilt and self-hatred. Then in the next scene we see the result: complete breakdown of trust. Othello screams about the handkerchief and Desdemona blubbers in bewilderment. It’s brutal and unsparing.
The play also takes up the theme of performance from Hamlet. But here the parts Iago and the others play are so shabby and pointless. By the end, Emilia and Desdemona’s last words are shattering because they are barely coherent. They aren’t rhetorical exercises. Instead of performing for the audience, we—the audience—seems to overhear them.
Othello murders Desdemona as a performance called for by his honor. He goes through with the performance, but without conviction:
Put out the light, and then put out the light.
Even Desdemona picks up his doubt:
EMILIA: O, who hath done this deed?
DESDEMONA: Nobody, I myself. Farewell.
Commend me to my kind lord. O, farewell!
OTHELLO: Why, how should she be murdered?