Saw this while out and about the other day and thought it resembled the Demilich logo or something. I love it when stuff like that just springs out at you. If I think back to the time when I first got into underground metal, I remember this as seeming like a part of metal tradition i.e. there's always got to be the unreadable logo that resembles some man-made or inorganic form, neatly tucked away in the right or left hand corner depending on the overall cover design.
Of course a lot of the appeal is going to in some way depend on how well the aesthetic elements fit in with the music, but it might also be the case that aesthetic acts as a vector for a given meaning based on how moving the music is on the whole.
Some favourites of mine have been Summoning, Beherit and Darkthrone I guess. You see the logo and then it just springs out and hits you. You know it's the mark of quality!