Islam has the same prohibition against idols that the Jews do from the Old Testament. When the Muslims took Mecca from their enemies, they went to the Kabbah and promptly removed all the idols inside and thus dedicated the structure to Allah and only Allah.
Simple as that, right?
In the deserts of Saudi Arabia long ago, the House of Saud (the current ruling house) made a pact with Muhammad ibn Abd al Wahhab and his successors. The House of Saud would support him religiously if he and his ultra-conservative sect supported them politically.
One of the principal points of Wahhabi doctrine is that idols are evil and that any kind of image is essentially an idol. Photographs, statues, etc. are all possible idols and thus evil. Even mirrors are not a great idea. There are no pictures representing Muhammad in Wahhabi Islam because the Wahhabis cannot allow anyone to venerate the Prophet in any way, shape or form that may imply Muhammad was anything more than an man graced by God to be His Prophet. This is why the Saudi government to this day is intent on finding any remaining traces of Mecca and Medina from Muhmmad's day and obliterating those traces to prevent any kind of shrines from being created.
Muslims who are aware of what the Saudi government is up to have lamented this destruction of their religious history, but they are powerless to do anything. In the meantime, those scholars who dig around in Saudi Arabia are more and more hiding their findings from the government to prevent more concrete being poured over the past.
Given the Wahhabi dislike, it's not surprising that the reports are indicating that the riots and violence around the world are being fueled by Wahhabi jihadists.
That's not to say though that it's just a few extremists. Let's review a simple fact. Since the oil crunch of the 1970s, the Saudis have been flush with cash and since then, one of their missions to placate Wahhabis at home is to export Wahhabism abroad. Wahhabi clerics have been spreading their message around the world for over 30 years. We are now seeing first hand just how far their message has spread.