It's just sad, but they're just following the example set by society - what the politicians did when they made fraudulent expenses claims (and isn't it sick to see those politicians moralising on Newsnight and the like?), or what the bankers did when they reward themselves massive bonuses for destroying economies and doing a crap job. Not that many of the kids themselves would be aware of these things, just an overwhelming sense of injustice and unfairness in their lives that caused them to lash out.
No excuse for the violence though, and of course in many areas it's gone beyond just pillaging for the "fun" of it. The police should have cracked down on the first night, which was a massive failure on their behalf.
Hopefully it has opened some eyes as to the problems of deprivation, lack of opportunity, and inequality in society.