I don't like maintaining the plastics so the more colour coding the better for me, but yes you can do too much, I think front fog surrounds and rear reflectors is probably enough and still looks factory.
I wouldn't mind the carbon upper grill and lower surround, think would look good as the black carbon would better match the rest of the plastics on the side of the car which are black, whereas front items and rear lower bumper are grey.
But the carbon jobbies are lottery money