Because player objects in Torque have Axis-Aligned Bounding Boxes, which means they cannot be rotated on any planes besides Z. If you think about it, setting the players rotation on another axis would literally turn the player, much like if you drive a jeep up a ramp. This isn't what you're looking for: you want them to look up, not magically rotate so they can see upwards while planking at a 45 degree angle. Vehicles, on the contrary, have Oriented Bounding Boxes. They can freely rotate on all 3 axes, so you can use setTransform() to make them turn in wild directions.
Ok thanks for the explanation
