Metal music for most of the people in the world considered this as just noise and is basically a "bad influence".
Well, I found an article that states that Metal music is educational according to one artist in South Africa.
According to this artist Parents need to be educated on the good influences of heavy metal music and how to deal with teenagers listening to the odd "bad" songs. Most metal music sympathizes with teenagers who are outsiders and teaches children to think for themselves about social issues.
Furthermore, most metal bands teach children that even though life may seem unfair, they need to "be strong and fight the good fight".
Parents have this fear of music which they themselves don't understand.".
Read more about the article here