One of the most glaring things which the nineties did - the leather-clad, spiked, homicidal elephant in the room, as it were, was that around the start of the decade, they practically invented black-metal as we know it today; Bands like Mayhem and Darkthrone took what they knew, threw it in a corner, and made something completely different - Something harsh, dark, and most importantly new; Nobody had done anything quite the same before. The bands which influenced them also did a lot in the early nineties and beyond, with albums like "Twilight of the Gods" by Bathory being unique and hauntingly beautiful in places, enough to forgive later albums like "Octagon", which are certainly evidence that the nineties happened.
Above: "Well hello, I don't remember meeting you in the 80's"
Bands like Enslaved and Emperor were among the first to take this newly forged genre to experiment with it - eagerly incorporating varying styles of synth and progression, spawning classics like "Frost" and "In the Nightside Eclipse". While Burzum continued to release albums which threw black-metal convention, new as it was, to the side, and unleashed many an album which has remained unreplicated. Albums which influence bands, even whole styles of black-metal to this day. Black metal certainly gave metal a boost when it was in it's hour of need - Thrash bands were beginning to wear checkered shirts, Glam was well and truly dead, and a lot of traditional metal was well and truly spent.
While black metal was, according to some, formed in opposition to death-metal, interesting things were going on in that genre as well. Bands like the ever-so-slightly-mainstream-but-never-mind Cannibal Corpse released classics like "Tombs of the Mutilated", and others, throughout the decade. On a more underground level, bands like Asphyx, Bolt Thrower and Obituary, among countless others reached their terminal velocity throughout the early nineties. While pioneers of the genre, Death, progressed and innovated their way through a number of album, many of which met high acclaim. Yes, death metal was alive and well throughout the decade, despite the fairly observable rises and falls of the style during that time.
Thrash probably took the biggest blow that decade, often almost vanishing, as the eighties-veterans began to disappear or sell-out, with very, very little in the form of new bands. It was only really after the nineties that thrash metal recovered at all, and in this case, I have to argue that, while the nineties may have sent thrash packing, it did not die. Many of the veteran bands weathered the storm, emerging from the other side with varying degrees of success, ranging from St. Anger to Ironbound. Out of the crash, in the early nineties, some thrash musicians turned their attention to other things. A certain Peter Steele, formally of Carnivore, was involved in an outfit by the name of Type O Negative, and together with majority-favourite Pantera, released solid albums throughout the decade.
And that, my friends, is why I believe that the nineties weren't that bad. Certainly, in the decades either side of it, metal has been a stronger force, that is quite plain to see. But nonetheless, there was always plenty going on - Metal is prone to being pushed underground... but that's where it thrives.
And now, links to all of the bands I mentioned, both directly an indirectly; (linking to metal-archives - I like to do this, as some bands have no Facebook, others no Myspace, etc. Metal Archives works well as a standard, in that just about every metal-band, ever, is on it)
Type O Negative