The first thing that comes to mind is to say this is relatively new thing for me, although I've been listening to it since my mid-to-late 20s - I'm now 63! - How time flies!
I used to be into long, instrumental pieces. Metal expresses powerful, deviation from the norm, often discordant, using rough, rather than smooth, textures, overall creating a sense of hardness and "things not being right". This I've come to find interesting and fresh.