Door traps don't work anymore because the doors you place don't face in the same direction when you place doors in a rotating pattern around a pressure plate. When you activate the pressure plate the doors don't close in and trap a mob. Placing the doors in the same position doesn't even change the orientation of the door, as it should close one way instead of the other way.
I could not reproduce this. I placed doors to the right of a pressure plate as I moved backwards in a clockwise direction and created a door trap.