It's because of the mechanics of the chopper. The Collective (the lever on your left) raises and lowers all rotor blades the same amount by raising the stationary swash plate equally so it requires by far, the most leverage. By setting the pilot on the right, the linkage from the collective lever is almost straight up to the swash plate making the extra leverage needed, more practical to apply.
With all blades set at the same angle for a full rotation, the aircraft should hover. Having said that, a single main rotor aircraft would rotate in the opposite direction from the rotation of the main rotor because of the torque involved. Thus at low speed or hover you need another force to prevent unwanted aircraft rotation. On a single main rotor craft you often have a smaller side mounted tail rotor to cancel out the torque spin,
However with a dual main rotor aircraft torque rotation isn't nearly so much of an issue because the main rotors rotate in opposite directions from each other so the torque reaction is cancelled out.
The Cyclic (what you might call the joy stick) raises and lowers only parts of the swash plate(s) on the fore and aft planes and side planes to lessen or increase the blade pitch depending where the blades are in their rotation to make the aircraft go forward, aft, or sideways. Since the Cyclic needs much less power to make these changes, the linkage doesn't need to be nearly as straight as that of the Collective.
On a multiple main rotor aircraft you move the plane forward by using more rotor tilt on the aft rotor than the forward one and vice-versa. Hover is with both rotors pulling equal load,