Judges in the Anglo-American tradition (England and its former colonies) have been making law since approximately the 14th century. It's called the "common law" and arose, and continues to develop, in response to the judges' need to decide cases where no statutory or constitutional law applies. A great deal of the law used in the state courts, and a little in the federal courts, is the common (or judge-made) law. So judges do, and should, "make law."
Usually when people say that "judges should not make the law," what they mean is that judges should not protect the constitutional rights of the minority contrary to the will of the majority. I think one can legitimately debate the extent to which the courts should protect the interests of the minority, but saying "judges should not make law" is not relevant to the discussion.