Jury members, to be poignant about it, are not trusted to be objective. They are peers of the defendant. Historically they were the proletariat, and hence uneducated, base, and instinctive.
Judges are supposed to be people who can be trusted to be objective. They are chosen (or, before they were elected, and politics became divisive) for their trustworthiness and objective scholarship. Historically they were well educated, of a higher class, perceived to be of a higher moral character.
The point is judges are expected to be mostly objective, and use external information responsibly.