Why was Concorde's cockpit so complex?
Why was this cockpit much more complex than any other modern day aircraft


Firstly, as others have noted, you imply Concorde was modern when you compare it with "other modern" aircraft. OK, it was a "jet-age" aircraft, but it wasn't a 21st Century design. it was designed before "glass cockpits" were possible, in the 1960s. There were no real multifunctional displays then, so there had to be a switch or dial for every possible action and every possible parameter the pilots might need to know about.

The main difference is probably the flight engineer's panel on the right. Modern aircraft have two pilots in the cockpit and no flight engineer. I imagine that increased automation in engine controls mean that the engine management by the crew is much simpler and requires fewer controls and dials. These are now typically located in the center of the main instrument panel above the thrust levers etc.

For comparison, here's (a somewhat poorly stitched panorama of) a 747 cockpit


Image by Eric Long, National Air and Space Museum, Smithsonian Institution

and a rather better photo of a 747-300 cockpit (though lower central controls are obscured) ...

Image &copy; aroosh


  or a fighter jet? 


A lot of the controls and instruments are duplicated in a two-pilot cockpit. In a fighter jet, you only see one set of instruments and controls. Also a one-engine plane will have a quarter the engine controls of a four engine plane. Fighters probably lack an APU.

Although fighters have additional switches etc for armaments, airliners have additional switches etc for passenger related facilities (seatbelt lights, a/c? etc), security (cockpit door), cabin-crew comms and so on. They also may have more fuel tanks and maybe more means to move fuel around in flight to trim the aircraft. 


  It looks to have much more buttons and controls, 


Modern glass cockpits just hide all that complexity, just imagine you could rotate 90% of what you see out of view.


  and very small(interesting) screens. 


There are no screens at all. There is a colourful moderately-complex artificial horizon instrument which also shows aircraft attitude and a few other things. The visual part is essentially mechanical rather than created by a light-emitting digital display.


  Also, its steering was much different than you would see in any other aircraft.


The shape of the control yoke may be slightly unusual but it operates the same was as any more common yoke design. You push it forward and back to control the pitch using the elevator (or elevons) and you rotate the top part left or right to control roll using ailerons (or equivalent control surfaces). There are buttons on the had grips to control a few functions. I think the shape was partly to make it easier to get in and out of the seat.

Heres a similar yoke design in an Embraer ERJ-145LR


Image &copy; Micheal Catchpole