For me, it's gotten to a point where I don't really care so much about innovation anymore.
What I do care about though is creative, inspiring to listen to music. You can be creative within boundaries that have been set already.
For example, Between the Buried and Me's Colors.
I realize this band and/or album isn't going to be to everyone's tastes reading my post, but Colors was one of the few albums in recent years in metal that I didn't just think "yeah, got some good tunes but nothing special" but was totally blown away.
It may not have been innovative in the sense of creating a new genre like Black Sabbath, but in a way I can't really describe, they pushed the boundaries by fusing heaps of stuff together, incorporating totally unexpected elements into the sound,like that Mike Patton vocal-esque thing into the middle of a heavy, brutal song, I never saw that coming at all upon my first listen, whereas most metal bands I hear these days are totally predictable in every sense.
They are showing what can be done if you're willing to put in massive effort and not resort to the same Bay Area Thrash band sound we keep hearing or the same old, old school death metal sound that keeps popping up.
I think progressive death metal in the vein of BtBaM is something with a lot of potential for growth. In the end, it's the artist that sets the limitation. If a band wants to mix up as much elements as possible and has the creativity to do so, it can be done.
I think a band like Nevermore really took many genres we know of, groove metal, death, thrash, melodic styles of metal and fused it into one amazing melting pot.
Petrucci might have shown us the direction a 7 string can take if you know how to play, but Jeff Loomis expanded upon the 7 string vocabularly that Petrucci gave us 10 fold.
We heard 7 string riffs people weren't doing before, we heard fucking insane sweep picked arpeggios like the solo on Born that utilized the 7th string like never before, at least from what I've heard anyway.
Re: Deathcore
True.......I only like about 4 deathcore bands so far out of the thousand shitty "mallcore deathcore" generic bands.
But again, a band willing to push forward with the sound rather than jumping on the mallcore deathcore bandwagon can do great things.
I think deathcore has shit loads of potential to push into innovative metal.
It's a matter of willingness to jump on that potential and too many bands have shown me that they wont.