The are nothing of the sort. The Constitution gives them one responsibility and one responsibility only, to cast the votes for president. It places one restriction on them, they cannot vote for a president and vice president who come from the same state as themselves. And that's it. They aren't a judge. They aren't a jury. The Constitution places those responsibilities in the hands of others.
You disagree with history then!
Meaning that they are free to vote for the candidate they feel would be best for both the people that elected them, and for the country. If they were restricted to voting as the popular vote in their states went, why bother meeting in their respective states to cast their votes? The Secretary of State, or other election official of the state could just as well send the electoral votes to Congress, or just a report of the popular vote. Of course their is no Constitutional requirement that they be elected by the people of the several states at all. The Constitution says:
Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress: but no Senator or Representative, or Person holding an Office of Trust or Profit under the United States, shall be appointed an Elector.
They were supposed to have some judgment and freedom of action. In fact they were supposed to form a buffer between the masses, with their predilection for "Snake oil salesmen", and the office of the Presidency.
Decades of "Democracy" at the expense of the Republic created by the Constitution, has gotten us that snake oil salesman. One with many personal foreign entanglements, far more than any previous President.