>I've been listening to various forms of metal (heavy metal, death metal, metalcore, deathcore, etc.) for over 20 years, and I never once (not even once) even thought to think about associating negative emotions to the music. In fact, it's the exact opposite reaction.

Agreed, it's energetic music (that I mostly lift to) not "hey man, I wanna go home and kill myself" or "hey man I wanna kill all my neighbors" music.