Everything you name is more a symptom of a culture of violence, not a cause. Violence is glorified in music and on television BECAUSE we are a culture of violence. Violence is used more often as a means BECAUSE we are a culture of violence.
The question is WHY are we a culture of violence.
To quote a favorite movie of mine:
Fear leads to anger. Anger leads to hate. Hate leads to the dark side.
Think about it.
Ultimately, it all leads to an abandonment of God. Many people simply freak out when they hear the mention of God! It automatically invokes an image of wacko religious fundamentalist creationists, who want to preach at people and cast judgment, while condemning them to hell. I guess this is a popular image because it is so easy to find unappealing. The fact is, humans who have no faith in something greater than self, will always lose their moral foundation and revert to the animals they once were.
To grasp an understanding of what I mean, you really have to examine the "creation" from the perspective of understanding I have about it. The Bible speaks of God creating the heaven's and the earth, light and dark, and then, the animals and plants, and finally, man and woman. This all supposedly happens within 6 days, and on the 7th, God rested. The first thing is, we don't really know how long a "God Day" is, it might be billions of years in "Human Days", we simply don't know this. Furthermore, we don't really know what is meant by "created" because the Bible doesn't describe much about that process.
After creating Adam and Eve, God tells them to "go forth and replenish the Earth." This is an important phrase... replenish the earth, means to re-populate it... re-build it... as if it were in existence in some state before. So this leads me to think, Adam and Eve were not the first humans on Earth, they were the first to be "created" by God. To be shaped in God's image, to be instilled with Godly attributes of forgiveness, love, compassion, etc. Before this time, all humans were Neanderthal, primitive, barbaric, animals. God enabled man to go forth and replenish the earth with humanity, modern man, the knowledge, wisdom, and understanding of his surroundings. We were created in his image, not duplicated from him, we are part primal animal, and part Godly creature. Therefore, within every man, is the instinctual primitive inclination to revert back to primal animal roots.
When man abandons God, he naturally reverts back to what he was before God created him in his image, a barbaric animal, with primitive instinct of an animal, no compassion, no love, no humanity. It is impossible for us to be anything else. It is only through God's creation of man, that we became civilized, and without it, we simply revert back to what we were before.
Step back for a moment and consider this... How many times in your life, have you heard one of your elders tell a story of when you were a child... something you did with your Uncle or Aunt, or something your Grandparent did for you when you were little? You didn't remember it, but you may have recalled it after they mentioned it. As time goes by, humans tend to forget things, memories are overwritten, and things become locked deep into our subconscious minds, we don't remember them, so we never speak of them to others. Generations pass, and important details escape, the next generation has less information than the one before. We learn new things, but forget the old things. This has happened for millions of years, and we have simply lost our past. What we are left with, are the vague recollections of what transpired in the beginning, stories and montages that have been told and retold, embellished and translated, and we have a very incomplete knowledge and understanding of the past. Nevertheless, it is somehow ingrained in every human, the inclination to worship something greater than self.
We are the stewards of the planet, we are the responsible species. No other creature is concerned with the environment, endangered species, global warming, etc. No other species is concerned with poverty, hunger, or war. No other species is compelled to look into the skies and attempt to spot near earth objects, or observe sun spots, etc. Only humans have this level of concern and sense of responsibility. We can study colonies of ants and realize, they are much more structured and complex in regimental organization than humans, we can observe the bees and see they have a much more sophisticated means of communication than humans, so we know that humans aren't necessarily the "most intelligent" of all living things. Yet, we are the species with the ability of cognitive thought, and we are ironically, the only species with the inclination to worship something greater than self. Curious, that!