Because positive discrimination is still discrimination, and if I'm assaulted on the street, I don't want my case file to be dumped at the bottom of the pile just because I don't listen to the right kind of music.
Right, but the complicated nature of a "motive" is not encapsulated by the binary characteristic of "was the victim an ethnic minority or not".
If I really hated horticulturalists, to the point that I wanted to punch one when I see one on the street, what's the difference between that and...