Jury's have traditionally played the role of finders of fact. They are generally more representative of the population as a whole, than one male or female judge would be, which is a characteristic we traditionally value in democratic societies. The jurymen are seen as peers of the defendant, whereas the judge simply interprets the applicable law. Additionally, the jury takes the power to sentence someone to prison, or find them liable in civil proceedings, out of the hands of one person. I don't think it's a matter of the judge being "bought" but rather the benefit of having a diversity of opinions and backgrounds.
