OF what use can knowing color genetics be?
Well for one, for producing scertain colors - I've heard the line so many times. A good horse is nver a bad color. You can't ride color. Or the person who always says color doesn't matter and yet you take 2 identical horses in physcial traits and temperament - one a plain sorrel and one a flashy buckskin - people will want the color every time. Color Sells. Color makes people happy and therefore is a desirable characteristic to know. Caveat: A good looking sorrel can be nicer than a poorly colored buckskin too :)
Another useful charavteristic for color is in pedigree verification. if you know that 2 sorrels cannot produce a palomino and yet thats what the pedigree says - you know further investigation is required. Either its not a palomino, or one of the parents was registered the wrong color or one of the parents listed is not actually one of the parents. The BRIDGEquine research database flags horses who's colors do not match up.
Color genetics are fascinating to learn and really not that complicated if you just want a basis aymans idea on color variations.