well i think both those issues are at play here. there's the larger stuff which is that lots of youths in poor areas feel very alienated politically, socially and economically, and in how lots of people feel disconnected from society and pessimistic about their future it creates the circumstances in which people don't mind about causing havoc and decide not to care about the local businesses and local areas and local people as people normally would. that's there, but it doesn't explain why people decide to engage with the riots personally on an individual level, why they are personally going out of their way to torch a bus or personally grabbing a tv and some aren't or the lack of any clear purpose to it, and there is where you have mindless thuggery of people enjoying destroying stuff and free stuff coming through.