Hi Thorsten,
You are right, for the airplane it makes no sense.
But for the pilot and his/her feel of the aircraft it is absolutely essential. The pilot can feel what is happening, if he pulls up or makes a corner. Very hard to explain to a non-pilot (or even to a pilot as this is so essential that it is almost an unconscious thing). This is also what I try to bring to this simulator because this aircraft feeling is completely missing and in my personal opinion it is the most important thing. It determines if an aircraft is flyable at all. It determines if the aircraft is easy to fly. The proper adjustment of the stick forces (also against each other, so pitch and roll forces) is one of the most difficult things in aircraft design.
In effect it is so essential this 'feel' (or in case of 'fly by wire' the 'artificial feel' as it is called) is required by the civil authorities. There is are requirements for the magnitude of pilot force, the stick-force-per-g and also the rise of the stick force (over airspeed). This also has to do with longitudinal stability, as the stick force direction change due to airspeed is 1:1 linked to it.
Civil aircraft (so including fly by wire aircraft) must have this. Airbus for instance tries to make this feel the same for all their aircraft, so that the pilot training for one airbus type to the other is minimal.
Military aircraft of course do not fall under the civil authorities and basically can do what they want. An F16 is a longitudinal unstable aircraft (except when supersonic as the aft shift of the wing aerodynamic center moves the neutral point aft of the CoG and thus makes it stable).
D-ECHO,
The calculations I used are implemented in JSB-sim. You can find them in the extra500 folder: extra500-flight-control.xml
The basics are not very complicated and I think there are some comments for what is what. For your aircraft to find out what the hinge moment coefficients are will however be very difficult. So unless you know exactly what you are doing, you have a really good understanding of flight physics and you have good data for your aircraft, I would refrain from using our code.
Cheers,
Eric