I have much respect for Desmond Tutu, but other than the sentence I bolded, it's evident he knows very little about terrorism, and perhaps should look into it closer because addressing it publicly.
Peace2 is correct that terrorism is not new. I've posted before that long before the US had 9/11, many of lived with it as a daily reality, albeit in the form of smaller attacks. There is/was the IRA, PLO, basque separatists and many others in various countries. So when he says why it's taken so long, I have to say: where have you been?!
It's not poverty... it's greed. When one country takes the land of another and calls it theirs leading to decades of bitterness and hate that festers and is passed from one generation to the next, the facts can sometimes become blurry because one only sees the hate, but not the root cause. And this is why it's so important to refer to history.