The biggest obstacle to originality in genres of 'alternative pop' like metal is the emphasis on the 'scene'. Despite all of the talk, most metalheads, skinheads, punks, etc. that I know aren't really 'in it' for the music so much as they are 'in it' for a place to belong. Metal is more than just music; it's a culture and culture is poisonous to original ideas.

You don't really see many (if any) metal musicians who don't look like metal heads. It's almost like theater on the bands part (I don't know about England, but in America we even call them 'shows'). These guys dress the part and the second they break that mold they are branded 'sellouts' by a bunch of whiny teenagers who, nevertheless, are the main source of income for the musician.
Imagine if a band came on stage dressed in a plain button up shirt and slacks? Or a tshirt and sweatpants? The whole community would lose it. Many people wouldn't even listen to the music at all because they would be too busy hollering about how the band wasn't as XxHardxCorexX as they are. When a community doesn't even allow a band to dress how they want there is no way in hell they will allow them to write original music.

In short, most alternative pop cultures are full of conformists and showmen. The only solution I have for something like metal is for the musicians to completely abandon the community and disregard their fans. It might also be helpful to move away from the 'fretboard masturbation' mentality that is so prevalent among rock communities.

But in my opinion, metal is for the most part obsolete and was rendered so long before it was born. Music like this, this, or even this expresses to me everything metal strives so hard to express - It's sinister and has the energy of anger and rage. It's violent and full of turmoil and it despairs. It expresses all of these things, but it does so with one instrument instead of 4+ and without any special effects. It has extremely daring and original chord progressions (and lots of them, too). All of this is contained within a very logical form that allows for the principal ideas to reaffirm themselves and make large scale musical 'arguments' that are greater than the individual melodies themselves.

Where do we find this kind of quality in 'alternative' music?