Clarification: I said I don't believe in prosecuting hate crimes. I meant I don't believe in classifying a crime as a hate crime. It should be prosecuted as assault and battery. "Why" is pointless.
Well, not pointless -- it should be mentioned by a prosecutor during trial as (part of) motive, and during sentencing when determining the likelihood for rehabilitation. However, I do agree that there shouldn't be separate charges or extra penalties for "hate crimes".