737 is a fully mechanical aircraft, it can be flown without hydraulic power with the exception of the rudder wich is hydraulically actuated.There are a lot of modes to move a surface like an aileron, the simplest way are the cables from the pilot controls to each surface.As the planes become bigger and bigger the surfaces becomes more heavy to move.A servo actuator was added to remove forces to the pilots, this is the 737.The aileron actuators for example (one for each hyd system) are in te main wheel well, far from ailerons, and near of them there are the 2 AP actuators.These actuators simply moves pushrods and torque quadrants, that will move cables to the ailerons and to the wheels.Whitout hyd power the primary flight controls are still functional.The difference is the rudder wich uses a different method.The rudder is mechanically controlled by cables until the actuators, the pusrods will move the actuator valve and the rudder will move only if pressure is present. Why the rudder is different is because it have the yaw damper wich moves the rudder without moving the pedals.There are a lot of planes with this kind of systems.One for example is the CRJ.Cables run from the column to the actuators, then the actuator phisically move the surfaces.If all controls are made in this way a display must show the surface operation as there is no way (except for a force increase) to know if the system works.Advantage?As the cable must not use force to move the surfaces, they can be smaller, so less weight, but at least 2 hyd lines are used to feed the surfaces.The fly by wire solution will remove cable weights as the actuators are directly controlled by electrical wires.

In my opinion, it's essential that both pilots get some mechanical, tactile feedback on what the airplane and its control surfaces are actually doing.This is especially important in emergency situations when all the computers take a dump.Just look what happened to the poor guys on AF447.

AF447 I believe had those information available and it did not help it one bit. Also, as mentioned, you have direct link from control collumn to control surfaces. Therefore controll collumn position is the same as control surface position (minus rudder, maybe). If not, then you have bigger problems at your hands.