One interesting variant, is the case where the Host opens a door without knowing if that door had a goat. Expressing relief that he opened a goat door, he asks you to consider switching doors.
IIRC, you get less information in this case, since there was a 1/3 chance that the host would accidentally pick the "car" door, but you still have a 1/2 chance of winning by switching.
No, you have a 1/2 chance of winning after a door has been opened. However, you also have a chance of losing on that reveal. Something you don't have in the normal variants. (That is, in normal variants, you only lose at the end of the game. This one, you could effectively lose when the host opens the actual winning door.)
So, your overall odds aren't as different as it seems. Just you have a much better odds of winning by switching, if you are still in the game.
IIRC, you get less information in this case, since there was a 1/3 chance that the host would accidentally pick the "car" door, but you still have a 1/2 chance of winning by switching.