Metal has went backwards since the 80/ 90's.... Was cool as fuck then, pantera, G n R, the big 4...
Can't realy think of anyone taking it further...
You're not really paying attention. Or not a truly exploratory/dedicated fan.
The world of music that falls under the umbrella of heavy metal has become vast. The development and fleshing out of substyles and the insane improvement in the technical proficiencies of the players has spun far, far beyond where it was even as recently as 10 years ago.
(Some strains of extreme metal have become homes to some of the very greatest instrumentalists in all of music, period. Where guitar playing experienced an epoch of sorts in the '80s, metal drumming has done during these past 20-odd years. Some of the performances are at the very cutting edge of what is thought to be possible.)