Right, fly-by-wire takes air data gathered from all kinds of instruments and interprets it using the flight computer, then it takes pilot inputs and translates them into the required control surface deflection. For example, a pilot flying at 1,000 ft may want a specific pitch rate, so he pulls back on the stick a specific amount, and the flight control computer moves the control surfaces 1 degree to give the pilot that pitch rate. Now, imagine the pilot is at 45,000 and he wants the same pitch rate, so he pulls back on the stick the same amount as before, but because of lower air density, the control surfaces aren't as effective, so the flight control computer will see this, and use a 20 degree deflection to get the same commanded pitch rate. Fly-by-wire also allows the pilot to have "hands off stability", which means that the pilot can point the aircraft where he wants to go, and the aircraft will stay on the desired path, regardless of wind gusts, changing air density, etc... Fly-by-wire also allows aircraft to be designed to be unstable, meaning their center of gravity is behind the center of pressure, instead of in front of it. This means that the horizontal stabilizers will have to generate lift in the same direction as the wings, instead of opposite it. Doing this increases the overall lift vector, which in turn allows increased maneuverability. One other advantage of fly-by-wire is it allows the pilot to make any control input, however, it won't let the aircraft fly beyond it's operating envelope, so it keeps the aircraft from stalling, or structurally damaging itself. Fly-by-wire makes flying more simple, and really makes stick-and-rudder flying a thing of the past, so if you really want to experience fly-by-wire flying in flight simulator, turn the difficulty down to easy, use auto-rudder, and fly in no-wind conditions. So really, fly-by-wire has been part of flight simulator for quite some time now.
