if you randomly were to run your hand in a basket of Norwegian black metal, and pulled one out and played it, it would likely (not ALWAYS... - likely) be music on the same level as rock music more or less. A few power chords for a verse, a main riff... Scandinavians as a people are very musical and good at their music so you can always come across in any genre good interesting bands. I don't however believe many would argue the Norwe black metal scene was not an example of how rich metal music is, to say the least. If you needed to show an educated but-non-metal musician some metal to demonstrate the musical wealth of our genre, that scene isn't the first one you'd think of picking from (unless it's a complete exception like mid/late Emperor). You'd pick prog metal, you'd pick perhaps death metal known for pushing the envelope as a whole...mathcore type material like Meshuggah or Periphery I instrumental with their polyrhythms...
that black metal scene was about achieving a sound, not so much writing memorable song. The emphasis was clearly on sound, not song-writing.