My 4 possibly controversial opinions on metal, that kinda go hand in hand:
1. Most "true" black metal only sounds evil, savage, or dark in 30 second iTunes samples. The songs themselves are repetitive and boring as fuck, and go absolutely nowhere, which completely kills the aggressive nature. This is true of even the so-called "brutal" black metal bands, such as Dark Funeral, Marduk, and 1349.
2. That being said, Burzum and Xasthur are amazing, because they don't try to come off as aggressive. The "droning" type of songwriting works for that.
3. Nile's album "In Their Darkened Shrines" is at least ten times darker, more epic, eerier, and it has more evocative power than any "true" black metal album I've yet heard (other than the two bands mentioned in #2). This is because they keep things interesting, change the riffs around, and then use epic moments to highlight the song and provide a contrast to the brutality.
4. Hell, I've yet to hear a band that can evoke an atmosphere and give me goosebumps in ways that Nile's (BSOV-Shrines) music can.