put it this way:  the hippies seemed especially butt-hurt about the 50s and so chose an aesthetic in a REactionary sense - you're up tight, we will be loose.  Metal was counter-rebellion, but at the same time didn't react to the permissive hippy culture in such butt-hurt, resentful fashion.  Sure, the metal aesthetic frowns upon the "looseness" of the hippy culture, but metal is not exactly "up tight."  I agree with ANUS that metal is the modern-day standard bearer of Western Romanticism, and in this sense, is more than simply a counterreaction to the permissive 80s in the way that the hippies were a reaction to the 50s.  But it does explain why metal bloomed in the 90s.

I do find this interesting.  Here is what I will add:  the hippies seemed to be a true opposite (aesthetically and idealogically) to the 50s.  However, the aesthetic and ideology of death meal and black metal of the 90s is not so much an "opposite" of the hippies but more of an "exaggeration" of certain hippy ideals like "freedom" and excess.  Aesthetically, death metal and black metal seems to say to the hippies:  you want freedom? you want excess? you want lawlessness?  This is lawlessness!  And here is the horrifying conclusion.

The world was nice and diverse before multiculturalism, in fact probably more so. Cultures were allowed to flourish of their own accord without being forced to live with people of all cultures, sacrificing essential aspects of thier own identity to accomodate them. This works both ways though, both cultures are worse off in this situation then before.

...

However,i am for the cultural exchange of ideas.

yes.  good points.  and with modern technology, cultures can exchange ideas so easily and rapidly that isolationism might as well be encouraged to simply stem the tide just a little bit.  peoples don't need to physically travel to learn about other cultures.  It's impossible to be isolated, nowadays, in the sense of the ancient Mayans.  Multiculturalism doesn't need to be pushed any more.  Everything is in place for the multiculturalist, it's all there at their fingertips.  The battle has been won, now let's see them transform the world (I won't hold my breath).