There's one similarity between the embassy-centred violence in the Middle East in the past week and the riots in Britain last summer that sticks out at me. Indeed, it's something common to all instances of members of an underclass doing something shitty: all attempts at explanation in terms broader and more sophisticated than the typical reactionary 'evil-doers do evil - burn them!' are accused of excusing or justifying the acts. Those who tried to point to the socio-economic causes of the riots were accused of justifying them, or taking the rioters' side.
Explanation is to justification what correlation is to causation: the one is not the other.