Ah, Dunkelheit.
Anger and dissatisfaction are immature emotions.
A very immature statement. Many times, anger and dissatisfaction are entirely appropriate reactions to the environment. Furthermore they are positive emotions because they provide impetus toward change. If you sit in your prozac fog eating what you're fed by the mass media, afraid of your own shadow, afraid of your very emotions to such an extent that you try to deny your animal nature, you're going to be sitting in that very same prozac fog 20 years from now, wondering why nothing has changed for you.
Part of metal is a celebration of the emotion of hate. In certain situations, hate is an entirely appropriate and healthy emotion and is once again an impetus toward positive change. Not everything good is entirely pleasant.
The statement that metal is simple and therefore somehow inferior is a straw man for a number of reasons. First, complexity is not necessarily desirable. Not everything needs to be the Goldberg Variations. If it is, complexity loses its meaning. In fact, complexity as an end unto itself has already lost emotional meaning-- it becomes an exercise in dexterity and pure math, sacrificing feeling.
There are bands like Meshuggah which in my opinion are rhythmic exercise, complexity for its own sake. These bands feature bizarre time signatures which make most classical arrangements look absolutely pale.
So first, I disagree with your thesis that complexity is necessarily desirable. Second, I disagree with your thesis that metal is somehow less complex than classical or jazz, which is simply not the case. The fact is, metal encompasses a breadth of substyles far larger than jazz, amazing considering the comparatively short time that it's been around. At times, it's very complex indeed, too much so for its own good I think: the true aesthetic of metal does not lie in complexity for its own sake.
Distortion and pounding drums push parts of the emotional scale that are simply unavailable to traditional classical and jazz. If you are unable to find beauty within the static, that doesn't necessarily mean that the beauty is not there, and is no indictment of metal but is in fact an indictment of you.
If the emotions expressed in metal are somehow unacceptable to your fragile psyche, perhaps you should examine why that might be.
What's so frightening about it?
Classical and jazz are just pop music, self-aggrandizing protests to the contrary notwithstanding. Particularly in the case of jazz, they are also dead abstraction, saying nothing, connected to nothing, meaning nothing. They are both absolutely dislocated, uprooted from their cultural origins. Are you drinking at a 1930s black after-hours speakeasy? Are you a member of the German aristocracy? If not, your investment in your identity as a member of some sort of jazz/classical literati is pretentious: you're going through the motions, pretending to be something you're not. In fact, the originating cultures of both jazz and classical would find you silly, pretentious and contemptible, for a variety of different reasons.
Quorthon, Black Jesus, Varg Vikernes and Abbath Doom Occulta are Diogenes, come to burn down your hoary dead temples.
Let me give you an example of a Man: