In any case, Shakespeare went to some pains to make Othello obviously different and foreign to the Venetians in the play. I have no problem with Othello being played as an Arabic type, but he would need to dress in a different fashion than the Venetians and should be at least a little swarthy so as to match the descriptions of "blackness" in the play.
His foreignness and perhaps, overt masculinity make him appear as a heroic figure to Desdemona and other Venetians, and his blackness makes him an unacceptable son-in-law to Brabantio.