Judges are professionals. They judge based on given laws and after given procedures. A jury have neither the knowledge nor the professional training to do this.
I am pretty sure that nobody here would like to have a "jury" of neighbours to take decisions on medical treatment instead of a trained and professional doctor.
Judges as professionals, of course, have to follow a code of ethics and have a board that control their performance. Also to note, there are higher courts, just to prevent any biased or incompetent decisions by judges.
The whole jury discussion is absurd and totally puts the whole point of a legal system aside.