Reasons why people hate hip-hop:

1. They believe it's not real music, since there's no instruments.

2. They believe the artists are untalented since they don't sing or play instruments.

3. They believe it puts on a bad image.

4. They are racists to black art forms.

Those are the 4 I've encountered... most people are just ignorant, using the first 3 reasons, but anyone who is on the 4th has problems.

It's not worth thinking about these people; just leave them alone. As long as they don't ruin your listening of the music you love, there's no point talking to them about it... very few will admit they're wrong.