@ Wolfgang, Leperchaun, and Deadite: those all sound on-point.
Also, upon further meditation, extremely gory lyrics seem to be a logical conclusion of Metal concepts. (I mean 'logical' in the sense of inevitable/determined.) I suppose that some artists would HAVE to be driven to dive deeper into pre-existing tropes of Heavy Metal. That they are repulsive to me, and not at all liberative, may just be a matter of predilection.
A human living in a developed country is in absolutely unique habitat(compared to all other animals) as he virtually never sees dead individuals of his own species(except through pictures/video). When observing the matter from this perspective, death metal lyrics(at least those of Autopsy) seem very profound. This alienation is also a reason for the increase of popularity of vegetarianism(the denial that killing & eating animals is innate for humans).
That seems especially real. A long time ago, I lived up in Nepal for 4 months, and already saw all sorts of bloodshed: corpses engulfed in flames at Pashupatinath; a sacrificial bull held down by 6 men while another man sawed into its throat, blood literally erupting a meter into the air; even down to my host 'cousin' holding a duck, slitting it's throat and taunting his nephew with that geyser of blood, later soaking the body in water to loosen the feathers, and ultimately dissecting it and cutting the heart open to show me its green interior.
I wonder if, in that kind of society, a mutilative Death Metal would be possible, to the degree that gore is casual, common, and thusly not very outlandish or brutal.
In another direction, I saw somewhere that certain Death Metal heads must play it, to stop them from actually murdering people.