You can find extreme elements in every society, be it mature (Norway, USA) or immature (Libya, Sudan) countries . People need to keep in mind that the ME countries where the most extreme protests took place, are the same countries that just toppled their dictators after decades of being ruled with iron fist (these dictators were covertly supported by the West). Add to this the extreme hatred towards USA in these countries, because of USA's foolish actions in Iraq and its support of Israel that represents true hypocrisy and injustice of USA.
This did not happen because of a simple and idiotic amateurish film, but this was a drop among many against ME orchestrated by USA. When your invasion of a country leads to extreme destabilization and safe haven for terrorism, which results in millions of lives destroyed, it will undoubtedly result in repercussions. It shouldn't come as a surprise to anyone that Islamic countries have very poor opinion of USA after its bloody conduct in Muslim countries. We have witnessed what American soldiers have done to innocent Iraqis in their dirty prisons etc. Do you think Muslims will forget these things overnight? No they won't, these are engraved in minds. In an age where information can be gathered by anyone multiplied in an instance, people will keep on remembering such cruelties. No one can justify the killing of innocent diplomats, but at the same time no one can legitimize the destruction of whole countries for oil and money.
We live in a harsh world where the strong can easily manipulate the attitude of billions of people via their propaganda channels. Where the strong can legitimize even the cruelest of actions resulting in hundreds of thousands of death. But we also live in a world where there still are honest people who are ready to sacrifice their own life for the betterment of their countrymen, like Mohamed Bouazizi who sacrificed his own life because of the extreme injustice towards his own countrymen. His protest spread like a fire, and today we see the continuation of that fire. They don't just protest against this movie, no, they protest against USA's covert operations that helped keeping these countries down for decades. They protest against the injustice being done to Palestinians and Iraq. Against Mubarak who were the man supported by the US. Yes they are uneducated and there are some extreme radical elements that is very disgusting (like the killing of innocent American diplomats). But their concerns are legitimate and reasonable.