Aircraft are very complex machines and for the sake of safety they are designed with a huge amount of redundancy, therefore they have a wealth of controls inside the cockpit.
Aircraft generally have about a half dozen different types of radios. Usually 2 communications radios, 2 navigation radios, radio direction finders, not to mention GPS receivers and weather RADAR systems make up a large bank of switches.
Many modern aircraft also have very sophisticated flight computers which can be used to keep track of the flightplan, fuel usage, and also monitor engine gauges to further increase safety while also reducing pilot workload. Of course in aviation, just the flight computer isn't enough, so the fuel usage info and engine gauges also have their own independent readouts separate from the flight computer.
There may also be an autopilot system which can be controlled manually through a set of switches and dials or, with the flick of a switch, tied directly to the flight computer.
Pilots and their aircraft have to be ready for anything. In the case of an engine failure or worse, fire, there are controls for each engine to shut off fuel flow and ignition, engage fire suppressant systems and the like. Furthermore the electrical system is subject to failure on many points, and a bank of switches lets the pilot isolate and disable problem circuits but still keep the rest of the electrical system running. The lights also play a large role, modern aircraft have many lighting systems, from cabin lights for passenger comfort to the flashing beacon light on the tail to the landing lights, the pilot must have control over all these systems, and thus a bank of switches for them.
There are of course numerous switches used to raise and lower landing gear, extend spoilers, adjust fuel loads and more not to mention the various instruments which give the pilot information about the aircrafts position, altitude, and speed each of which have their own switches and dials.
The cabin air system in modern aircraft may be very complex as well. In addition to providing pressurized air for high altitude flying, it will also need to have heat and air conditioning controls as well as supplemental oxygen systems and carbon-dioxide monitors.
There is a lot to do in the modern cockpit, and there are a lot of controls needed to get the job done. Modern computerized systems have been steadily reducing the number of switches in aircraft cockpits, but it has not and probably will never eliminate them entirely.