The new Joystick Base part looks quite simple, but looks can be oh so deceiving.
The main purpose of this part is to allow players to build custom flight controls. You can connect fuselage parts to the control base and it can rotate or translate those parts based on the assigned inputs. In that sense, it's like a multi-axis rotator and piston, which is very powerful. It is also able to respond to the player in VR when they grab the stick with their virtual hands.
The Part Properties for this part has several presets available to help you create standard control configurations: Joystick 2-Axis, Joystick 3-Axis, Yoke, Wheel, Lever, and Custom. There are several options available giving you incredible flexibility to create basically any kind of control you can imagine.
It's a beautiful fusion of flexibility and simplicity in a small package. Nicky went full wizard mode when he implemented this part.
And to all those thinking they're going to misuse this for the most random of purposes, I am one step ahead of you - WNP78