Is it okay for them to ignore the voters? Electing the president wasn't supposed to be a popularity contest, so of course they can, unless state law prohibits it. And large states should not be able to completely override the will of smaller states.
If the whole purpose of actually electing "electors" instead of just having votes per state was to send guys to Washington to actually deliberate, why have actual people at all?
Technically, the Founding Slave Rapists put TWO blocks in there to keep a madman from getting in.
1) The electors.
2) The final results have to be approved by Congress.
What should have happened is that someone should have said, "Oh My God, Trump is nuts!" and put a stop to it. They didn't.