Not just me that has noticed this then? Awesome!
The stuff usually on my playlists is Slayer, Dying Fetus, Panzerchrist, Cannibal Corpse, anything that involves Max Cavalera, Leng Tch'e, Hatebreed - pretty much anything that makes me want to punch through walls.
On the technical side, I appreciate bands like Cannibal Corpse, Dying Fetus et al, who are undoubtedly gifted musicians but I also love the rawness of dropped D. I used to have a guitar in a Max C stylee - b and e taken off, detuned to D and I used to love smashing the crap out of it (often played through my bass amp to get that more mental sound)
I just appreciate loud, angry music. That aside, I have quite an eclectic mix of music that I enjoy - anything from Slayer to Skinny Puppy, Tori Amos to NWA and Cypress Hill.
The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown.