I always cringe when I hear or read things like "grunge killed metal". What the fuck?! It was only that the media created another hype and it was clearly up to the listeners which bands they supported back then (with their money). I mean, where did all the people go? Do you think they all died when they first heard Smells Like Teen Spirit? Come on...
You are spot on. Maybe the metal bands themselves at the time should have listened to your advise. Most metal bands changed to a more mainstream sound during this time or just quit altogether.
I personally always listened to metal, hated the alternative and grunge scene except for Alice in Chains. But looking back I'd take Soundgarden and Mother Love bone, Pearl Jam etc over Nu-metal gimmick bands like Limp Bizkit and Papa Roach.
Thankfully there really is not a new 'trend' in the rock music genre that is fucking it up for metal bands. So even bands that previously wussed out like Metallica and Anthrax are back to making heavier/thrashier albums again... hopefully