While I think the wings in-general could use a rework, the control surfaces especially need one. The options you have for shaping them are abysmal, as you have no control over how they taper with the wing's shape.
Example:
In this image I am making a custom wing with fuselage parts. I want the control surface of the real wing to match the blue rectangle I've drawn in the image so that my custom control surface matches it, but I am unable to with the way the control surface editor works. This is annoying, and I would love to see it fixed.
There should also be the possibility of making a fly by wire, notably on fighter jets and space shuttles.