Apparently extended range guitars are why modern metal sucks. At least that's the case if you ask guitarist Bernth.
Bernth has taken to YouTube to drop a sort-of industrial track with plenty of shred called "Still Shred", which explains why all the downtuning in modern metal sucks so bad. With lyrics like "The kids are tuning lower every day. I thought this trend would die and fade away. Pitches barely audible, higher strings optional," it really couldn't be any clearer where the dude stands.
Personally, I disagree. Downtuning is yet another stylistic choice in an endless sea of stylistic choices, all of which can either be done very well or very poorly (and even that's subjective). Sure, maybe a record that tunes way down has some pretty indiscernible riffs, but maybe that's also the point? Nobody is listening to a grimy slam record because the production is pristine – you want that filthy, disgusting low end blowing out your subwoofer. On the flip side, there are bands like Tesseract and Periphery, whose use of super low end notes couldn't possibly be any clearer production-wise. Intent and perception are two things, and they're often at war with one another.
Anyway, do whatever the fuck you want. Art is art and you can make it however you want to make it. Tune down to drop Z and level your entire neighborhood with a 36-string guitar, who cares? And by the way, none of this is a shot at Bernth. The guy is incredibly talented and has made himself a successful career with the guitar. It's just this particular opinion that I'm not too sure works out.