Each individual legal rule isn’t formulated according to a free-ranging consideration of what’s “beneficial to society.” It would be impossible to administer such a system of rules based on
ad hoc policy considerations.
The rule here, the Seventh Amendment, confers a right to a jury trial when one would have been required under English common law at the time the seventh amendment was written. Roughly speaking, in the English system, cases involving monetary damages were handled in courts of law with juries. Cases that involved injunctive relief (orders to do or not do something) were handled in courts of equity with decisions made by judges.
