Well if you intend to allow setting a specific setting as a favorite wouldn't that mean that each color selector has it's own favorite?
Well, imagine the color selector, with the 4 sliders, just as now, except with favorite buttons at the top. I can either make these buttons set the sliders to the same 4 values despite what value you are changing, or save favorites based on the value you're saving. The first way you can easily change water colors etc to the same value or similar favorite values without setting them twice, the second way you don't get useless values like blue sun light as favorites.