Anecdata ahead. There are different sub genres even within such niche genre as death metal. I love melodic death methal bands such as Dark Tranquility (those in the know would recognize it just by looking at my username), In Flames, and Insomnium. Their lyrics in general are not about extreme forms of aggression as article suggests, but revolves mostly around feelings of loneliness, apathy, acceptance and imminence of death, despair etc. First and foremost I listen to it because it is a very good music by talented musicians, just in their choice of genre. There is definitely an element of appeal in it in its “death” aspect though and I thought about it a lot over the years. Contrary to its general tone and lyric content melodic death metal does make me feel relaxed or energized, but generally brings positive emotions. I came to the conclusion that it is about unearthing all the fears and negative emotions that this music brings up in lyrics, acknowledging them and making peace with them instead of suppressing them.