I have always felt a bit uncomfortable with the concept, as it is not quite the citizen participation the system originally designed for, but I have always felt I would be very good at this, and if such a thing ever came to pass, I would gladly sit through boring hearings in the interest of improved justice for my country and its citizens. I can listen to unpleasant information without being traumatised; I understand general principles of law; I can and have overruled my own prejudices; I understand information quickly. What's not to like?
But these would be government positions, and it occurs to me that some government agency would start keeping tabs on whether I convicted or acquitted group A or group B more than I should. It is not hard to imagine a world in which professional jurors were warned, retrained, and eventually let go because the outcomes were not what some agency thought was right, regardless of the merits of each individual decision.
While I think there is a conservative/liberal issue here, I don't think that is all of what is in play. My brother, who is quite liberal, would have much the same problem, I suspect. He would attempt to decide each case on its merits, and be relatively immune to counting up whether he was in proper parameters this year. Eventually a year would come when he would be accused of evil. He would know this was not so. He would refuse to back down. He would not be re-offered a position the following year.