I do not understand the purpose of hate crime statistics.

If a person goes around murdering people for instance - it kind of stands to reason that this person has a some form of hate going around in his mind. What does it matter if he hates only black people or people that wear orange hats? What matters is that he is a murderer. Murder has always been against the law around here so lets focus on getting rid of murderers instead of trying to divine what is in their hearts. What additional benefit does it gain us in attempting such divination?