I have heard of a lot of people that want a color picker, but most of the time they are unable to know what color theory is. I don't think I have ever needed to learn color theory, but learning to mix colors to get what I want is something I can't do without.
When I see a color that says peach or facial color, I see it as their opinion. My opinion is only matches the colors I see, or want. So even if you have colors to chose from, I will still use the soft edge brush to spray colors to blend, and use the us dropper to pick the closest to what I want. I never get stuck with what is there. Every color I use was created by blending colors and the end result is the blend. If I want blush, I use red to softly add in without hard edges so it blends in. I don't thing any color you see in my art is an exact color, but if you have to know what color that was then you can copy the image and pick the color up with the eyedropper.
No matter what color you think it should be, ever color is effected by light, so even if you think it is the perfect color, it might only look that way because it is effected by the light, and that may only be a light over spray with a large brush to all the color of the light.
I can say I never understood color theory, but I know every color changes with circumstance. If every color was a pick by number then it would not be real art.