Actually, crumple zones increase the time over which the deceleration happens reducing g-force on the occupants body. So yes, they do work, accelerometers don't lie. Yes they cause the vehicle to be totalled easier, that's the point, the car is supposed to absorb the energy of the impact, not the occupants.
Think of it this way, would you rather run as fast as you can into a brick wall or a wall of foam? Yeah, the brick wall is stronger and can withstand impact better than the padded wall without being damaged. So why don't you choose the brick wall?