But, as we've seen, the analogy doesn't really hold up to scrutiny, and I still don't see the point in praising bands that are neither particularly revolutionary nor particularly good. There is, in my mind, value in a failed or at least incompletely realized experiment (for example, Cynic's Focus), but not much value in music that doesn't really push the boundaries beyond what is already known or in fleshing out the known in interesting ways. I don't see this as a 'silly prejudice,' but merely as a practical response to limited time and resources.
Here's another perspective. I don't know how much you listen to punk, if at all, but many punk elitists would say that almost everything of value in that genre had been produced before 1980. In my view, a lot of what was produced in the 1970s sounds juvenile and had little depth to it. Whilst it was fresh and original at the time, a lot of it too was a result of inferior musicians jumping on the bandwagon with ill thought-out ideas. Even the truly influential bands had a naivete about their philosophies.
So, moving on to the 1980s, not much was original per se, but it pushed the envelope further: an oeuvre of albums was produced which were faster, more aggressive, more politically intelligent, with better lyrics and more refined songwriting. And musicians who could actually play their instruments. In that sense, the originality of the 70s was overrated.
As you've probably guessed, I see in all of this a parallel with black metal. Whilst a good part of my favourite albums came from the 2nd wave and have a rarified atmosphere of rawness to them, I still think songwriting has progressed in the sense that albums have been produced which are more hateful, or more technical, or draw in more diverse influences, or in some cases just plain better-written. And I don't see why the fact that those albums were written in 2001 instead of 1991 should matter when the music is assessed on its merits.
If you don't see the quality of songwriting in the upper eschelons of modern black metal, there's not much I can do about that, but it seems to me that you place too much emphasis on originality. I don't believe in any automatic reverance ascribed to 2nd wave bands, unless of course it is earned by the quality of the music. I would have no hesitation to say that in my opinion Deathspell Omega's
Si Monumentum Requires, Circumspice is a more refined and more intelligently written album than anything by Darkthrone, except perhaps Soulside Journey. That is not a slight on Darkthrone, who rightly have carved their place in metal history, but similarly it should not prevent due recognition going to DSO. Taking the argument to the extreme example, if I invent a musical genre, something thoroughly original in both structure and aesthetic, but execute it poorly, does it automatically make a subsequent artist who flawlessly executed that style inferior to me? I don't think so.